Selective hydrogenation methods and catalysts

ABSTRACT

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a method for selectively hydrogenating acetylene, the method comprising contacting a catalyst composition with a process gas. The catalyst composition comprises a porous support, palladium, and one or more ionic liquids. The process gas includes ethylene, present in the process gas in an amount of at least 20 mol. %; and acetylene, present in the process gas in an amount of at least 1 ppm. At least 90% of the acetylene present in the process gas is hydrogenated, and the selective hydrogenation is conducted without thermal runaway. Notably, the process gas is contacted with the catalyst at a gas hourly space velocity (GHSV) based on total catalyst volume in one bed or multiple beds of at least 7,100 h −1 .

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 62/749,456, filed Oct. 23, 2018, which is herebyincorporated herein by reference in its entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The disclosure relates generally to hydrogenation methods and tohydrogenation catalysts. More particularly, the present disclosurerelates to methods for selectively hydrogenating acetylene, for example,in front end processes; to methods for starting up a selectivehydrogenation reactor, for example, in front end processes; and tohydrogenation catalysts useful in such methods.

Technical Background

Olefins are important monomers for the production of plastics. Forexample, ethylene and propylene are polymerized to form polyethylene andpolypropylene, respectively. Olefins such as ethylene and propylene aretypically derived from petroleum products through thermal or catalyticcracking of hydrocarbons. However, cracking provides a crude olefinmixture that can contain acetylene, which can interfere with thedownstream polymerization of ethylene and propylene. It can be desirableto “clean up” this process gas to selectively convert acetylene toethylene without substantial reduction of any olefins present or theacetylene itself to alkanes.

There are two main reactor configurations for selective hydrogenation ofacetylene in ethylene-rich streams—so-called tail-end (or back end)processes, and front end processes. In the tail-end configuration, theselective hydrogenation reactor feed typically consists mainly of C2hydrocarbons, and stoichiometric amounts of hydrogen with respect toacetylene are added to this feed gas stream to ensure an optimalconcentration of hydrogen (typically 1%-4% mol. %) in the feed stream tothe reactor. Carbon monoxide is typically not present in the feed streamin amounts greater than 2 ppm; in some conventional processes, CO isseparately added to the reactor inlet stream. In the front-endconfiguration, the selective hydrogenation reactor feed typicallycontains a large excess of hydrogen, e.g., 10-35 mol % of hydrogen,together with carbon monoxide, acetylenes, olefins and otherhydrocarbons. In a front-end deethanizer design, the reactor feedcontains a C2 and lighter stream, while in front-end depropanizer unit,the reactor feed contains C3 and lighter hydrocarbons. Carbon monoxideis generally present in such feed streams, in concentrations varyingfrom below 100 ppm to 3000 ppm.

Conventionally, front end selective hydrogenation of acetylene presentin an olefin rich mixture is performed by using optionally-promotedpalladium-shell catalysts. However, the activity of the hydrogenationcatalyst under the process conditions must be carefully limited to avoidthermal runaway (an uncontrolled feedback loop, in which heat from theexothermic hydrogenation reaction increases the catalyst temperature, inturn increasing the rate of the hydrogenation reaction, which provideseven more heat, etc.), which can result in an undesirable overreductionof ethylene to ethane and even in shutdown of reactor due to anuncontrollable temperature rise in the reactor. Conventional front endselective hydrogenation processes are so limited through strict controlof the temperature, which is kept below a certain temperature (e.g., arunaway temperature). Conventional front end selective hydrogenationprocesses are limited by gas hourly space velocity (GHSV), so that thetemperature due to the exothermic hydrogenation reaction required toclean-up acetylene does not rise too high, so as not to approach atemperature that may result in thermal runaway.

Moreover, reactors for such conventional front end selectivehydrogenation processes, particularly those containing fresh catalyst,must be started up particularly carefully to avoid thermal runaway.Conventionally, it was understood that the initial contact of thecatalyst bed with process gas (i.e., containing hydrogen, olefin andacetylene) flow must be made at low temperature to avoid runaway. But atsuch low temperatures, reduction of acetylene is typically not completeand so the acetylene concentration in the reactor effluent is higherthan the product specification allows. While process gas flows, thecatalyst bed temperature is then raised very slowly to a desiredreaction temperature at which the acetylene concentration meetsspecification. The temperature rise is often on the order of a degreeCelsius per hour, and so the start-up procedure can take over twentyhours to provide on-specification output. During the start-up period,the out-of-specification effluent from the reactor is often sent toflare.

In addition to strict temperature control, conventionally, duringstart-up the reactor is pre-charged with CO and pressurized withnon-reactive gases before the catalyst is heated. The composition of thereactor gas mixture is slowly shifted towards the process gas (i.e.,containing hydrogen, acetylene and one or more olefins). This startupprocess not only has safety concerns due to the use of a large quantityof CO gas on site, but it is also costly, due to material costs, to lostproduction time, and to treatment/disposal of the reactor output beforethe reactor is fully operational.

Accordingly, there remains a need for a method for selectivelyhydrogenating acetylene at high throughput, and/or at a lowconcentration of CO, but without undue risk of thermal runaway. Therealso remains a need for a method for starting up a hydrogenation reactorthat does not require pre-charge of the reactor with CO, nor inert gaspressurization, and/or that can be conducted in a short period of time.

SUMMARY OF THE DISCLOSURE

The present inventors have discovered that the catalysts describedherein have especially advantageous properties that allow for newmethods of selective hydrogenation of acetylene.

Accordingly, one aspect of the disclosure is a method for selectivelyhydrogenating acetylene, the method comprising contacting a catalystcomposition comprising a porous support, palladium, and at least oneionic liquid with a process gas comprising ethylene, present in theprocess gas in an amount of at least 10 mol. %;

-   -   acetylene, present in the process gas in an amount of at least 1        ppm;    -   hydrogen, present in the process gas in amount of at least 5        mol. %; and    -   0 ppm to 190 ppm carbon monoxide;

-   wherein at least 90% of the acetylene present in the process gas is    hydrogenated, and no more than 1 mol. % of the total of acetylene    and ethylene present in the process gas is converted to ethane.

Another aspect of the disclosure is a method for selectivelyhydrogenating acetylene, the method comprising contacting a catalystcomposition comprising a porous support, palladium, and at least oneionic liquid with a process gas comprising ethylene, present in theprocess gas in an amount of at least 10 mol. %;

-   -   acetylene, present in the process gas in an amount of at least 1        ppm;    -   hydrogen, present in the process gas in amount of at least 5        mol. %; and    -   at least 600 ppm carbon monoxide;

-   wherein at least 90% of the acetylene present in the process gas is    hydrogenated, and no more than 1 mol. % of the total of acetylene    and ethylene present in the process gas is converted to ethane.

Another aspect of the disclosure is method for selectively hydrogenatingacetylene, the method comprising contacting a catalyst compositioncomprising a porous support, palladium, and at least one ionic liquidwith a process gas comprising

-   -   ethylene, present in the process gas in an amount of at least 10        mol. %;    -   acetylene, present in the process gas in an amount of at least 1        ppm;    -   hydrogen, present in the process gas in amount of at least 5        mol. %; and

-   wherein the process gas is contacted with the catalyst at an overall    gas hourly space velocity (GHSV) of at least 7,100 h⁻¹ (e.g., 7,500    h⁻¹ to 40,000 h⁻¹) based on total catalyst bed volume; and

-   wherein at least 90% of the acetylene present in the process gas is    hydrogenated, and no more than 1 mol. % of the total of acetylene    and ethylene present in the process gas is converted to ethane.

Another aspect of the disclosure is method for starting up a selectivehydrogenation reactor, the reactor housing one or more catalyst bedseach containing a catalyst suitable for selectively hydrogenatingacetylene in a process gas comprising at least 10 mol. % ethylene, atleast 1 ppm acetylene, and at least 5 mol. % hydrogen, the methodcomprising

-   -   providing each catalyst bed at no more than a first temperature,        the catalyst of the catalyst bed being in contact with a first        gas, the first gas being non-reactive in the presence of the        catalyst at the first temperature;    -   in the presence of the first gas, heating each catalyst bed to        at least a second temperature, the second temperature being at        least 10 degrees greater than the first temperature, the first        gas being non-reactive in the presence of the catalyst at the        second temperature; and then    -   changing the composition of the gas in contact with the catalyst        from the first gas to a flow of the process gas while the        catalyst bed is at least at the second temperature; and    -   allowing the process gas to flow through the catalyst bed until        a concentration of acetylene at an outlet of the reactor is less        than 1 ppm.        In certain such embodiments, the first temperature is in the        range of 31-50° C., e.g., 31-45° C., or 31-40° C. In other such        embodiments, the first temperature is in the range of 35-50° C.,        e.g., 35-45° C., or 35-40° C. And in other such embodiments, the        first temperature is in the range of 40-50° C., e.g., 40-45° C.,

Another aspect of the disclosure is a method of starting up a selectivehydrogenation reactor, the reactor housing one or more catalyst bedseach containing a catalyst suitable for selectively hydrogenatingacetylene in a process gas comprising at least 10 mol. % ethylene, atleast 1 ppm acetylene, and at least 5 mol. % hydrogen, the methodcomprising;

-   -   providing the reactor with each catalyst bed having its catalyst        in contact with a first gas, the first gas being non-reactive in        the presence of the catalyst at the first temperature, wherein        the catalyst has not been contacted in the reactor with a carbon        monoxide-containing gas having a carbon monoxide concentration        in excess of 100 ppm; and    -   introducing a flow of the process gas to the one or more        catalyst beds, and refraining from adding carbon monoxide to the        process gas.        Such methods can further include raising the catalyst bed        temperature of each catalyst bed from no more than a first        temperature to at least a second temperature (e.g., before,        during or after changing the gas in contact with the catalyst        from first gas to process gas).

Another aspect of the disclosure is a method of starting up a selectivehydrogenation reactor, the reactor housing one or more catalyst bedseach containing a catalyst suitable for selectively hydrogenatingacetylene in a process gas comprising at least 10 mol. % ethylene, atleast 1 ppm acetylene, and at least 5 mol. % hydrogen, the methodcomprising

-   -   providing each catalyst bed at no more than a first temperature,        the catalyst of the catalyst bed being in contact with the gas;    -   in the presence of the process gas, heating each catalyst bed to        at least a second temperature, the second temperature being at        least 20 degrees greater than the first temperature, the heating        of each catalyst bed being performed at a rate in the range of        at least 3° C./hour; and    -   allowing the process gas to flow through the catalyst bed until        a concentration of acetylene at an outlet of the reactor is less        than 1 ppm.

Another aspect of the disclosure is a method of starting up a selectivehydrogenation reactor, the reactor housing one or more catalyst bedseach containing a catalyst suitable for selectively hydrogenatingacetylene in a process gas comprising at least 10 mol. % ethylene, atleast 1 ppm acetylene, and at least 5 mol. % hydrogen, the methodcomprising

-   -   drying the one or more catalyst beds at a temperature of at        least 50 C; then    -   cooling each dried catalyst bed to a first temperature in the        range of 31-50° C., e.g., 31-45° C., or 31-40° C., or 35-45° C.,        or 35-40° C., or 40-50° C., or 40-45° C.), and contacting the        catalyst of each catalyst with the process gas at the first        temperature; then    -   in the presence of the process gas, heating each catalyst bed to        at least a second temperature, the second temperature being at        least 20 degrees greater than the first temperature; and    -   allowing the process gas to flow through the catalyst bed until        a concentration of acetylene at an outlet of the reactor is less        than 1 ppm.

Another aspect of the disclosure is a hydrogenation catalyst compositioncomprising:

-   -   a porous support, present in the composition in an amount within        the range of 90 wt. % to 99.9 wt. %;    -   palladium, present in the composition in an amount within the        range of 0.02 wt. % to 0.5 wt. %, or 0.03 wt. % to 0.4 wt. %, or        0.04 wt. % to 0.3 wt. %, calculated on an elemental mass basis;        and    -   one or more ionic liquids, present in the composition in a        combined amount up to 10 wt. %.

Another aspect of the disclosure is a hydrogenation catalyst compositioncomprising:

-   -   a porous support, present in the composition in an amount within        the range of 90 wt. % to 99.9 wt. %, having a BET surface area        of no more than 10 m²/g and a pore volume of at least 0.1 mL/g;    -   palladium, present in the composition in an amount within the        range of at least 0.02 wt. %, calculated on an elemental mass        basis; and    -   one or more ionic liquids, present in the composition in a        combined amount up to 10 wt. %.

Another aspect of the disclosure is a hydrogenation catalyst compositioncomprising:

-   -   a porous support, present in the composition in an amount within        the range of 90 wt. % to 99.9 wt. %;    -   palladium, present in the composition in an amount within the        range of at least 0.02 wt. %, calculated on an elemental mass        basis; and    -   one or more ionic liquids, present in the composition in a        combined amount up to 10 wt. %,    -   wherein the hydrogenation catalyst has a BET surface area of no        more than 10 m²/g and a pore volume of at least 0.05 mL/g.

These hydrogenation catalyst compositions can be advantageously used inthe methods described herein.

Other aspects of the disclosure will be apparent to the person of theordinary skill in the art in view of the disclosure herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a set of graphs showing the concentration of acetylene andethylene in the output of a process described herein (left) and theoutput of a conventional process (right).

FIG. 2 is a graph showing the ethylene selectivity (left y-axis) of aprocess described herein (middle line) and a conventional process(bottom line) through several variations in CO concentration (top line,right y-axis).

FIG. 3 is a set of graphs showing the acetylene conversion (left) andethylene selectivity (right) of various processes described herein.

FIG. 4 is a set of graphs showing the acetylene conversion (left) andethylene selectivity (right) of various processes described herein.

FIGS. 5, 6, 7 and 8 are graphs of reactor temperatures for the startupexperiments of Example 6.

FIG. 9 is a graph of acetylene reduction selectivity with respect to COconcentration under isothermal conditions for a catalyst as describedherein and a comparative catalyst.

DETAILED DESCRIPTION

The disclosure relates to methods for selectively hydrogenatingacetylene (C₂H₂) by contacting an acetylene-containing process gas witha catalyst composition comprising a porous support, palladium, and oneor more ionic liquids, and optionally promoters such as silver, gold,zinc, tin, lead, gallium, cadmium, copper, bismuth, sodium, cesium, orpotassium. The present inventors have determined that such catalysts canunexpectedly provide for improved operation of hydrogenation systems byallowing for selective hydrogenation of acetylene without thermalrunaway under a wider variety of conditions than previouslycontemplated.

For example, in certain aspects of the disclosure, CO may be present inthe process gas, if at all, in only a relatively small amount (e.g., ina range from 0 to 190 ppm, or 0 to 175 ppm, or 0 to 150 ppm, calculatedon a molar basis). This can allow for processes to be performed withoutadding CO to a low-CO feed, simplifying operation and improving plantsafety.

In other aspects, CO may be present in the process gas in a relativelylarge amount (e.g., at least 600 ppm, or in a range from 600 ppm to20,000 ppm, or 600 ppm to 10,000 ppm). This can allow for high-COprocess gases to be used. In various aspects, the process gas can becontacted with the catalyst composition at a relatively high gas hourlyspace velocity (GHSV) (e.g., at least 7,100 h⁻¹, at least 10,000 h⁻¹, orat least 12,500 h⁻¹, for example in the range of 7,100 h⁻¹ to 40,000h⁻¹, or in the range of 10,000 h⁻¹ to 40,000 h⁻¹, or in the range of12,500 h⁻¹ to 40,000 h⁻¹). The present inventors have determined thatthe catalysts described herein can be used at unexpectedly high reactionflows without runaway. And in certain embodiments, the selectivehydrogenation is conducted at a relatively high temperature, allowingfor increased reaction rate and increased throughput. The disclosuredemonstrates that such methods of selective hydrogenation mayadvantageously provide desirable selective acetylene conversion and withrelatively little ethylene (ethene; C₂H₄) conversion without thermalrunaway.

Accordingly, one aspect of the disclosure is a method for selectivelyhydrogenating acetylene, the method comprising contacting a catalystcomposition with a process gas. The catalyst composition comprises aporous support, palladium, and one or more ionic liquids. The gasmixture includes ethylene, present in the process gas in an amount of atleast 15 mol. %; acetylene, present in the process gas in an amount ofat least 1 ppm; hydrogen, present in the process gas in an amount of atleast 5 mol. %; and 0 to 190 ppm carbon monoxide. At least 90% of theacetylene present in the process gas is hydrogenated and the selectivehydrogenation is conducted without thermal runaway. And another aspectof the disclosure is a method for selectively hydrogenating acetylene,the method comprising contacting a catalyst composition with a processgas. The catalyst composition comprises a porous support, palladium, andone or more ionic liquids. The gas mixture includes ethylene, present inthe process gas in an amount of at least 15 mol. %; acetylene, presentin the process gas in an amount of at least 1 ppm; hydrogen, present inthe process gas in an amount of at least 5 mol. %; and at least 600 ppmcarbon monoxide. At least 90% of the acetylene present in the processgas is hydrogenated and the selective hydrogenation is conducted withoutthermal runaway. In certain such embodiments, the contacting isperformed at a GHSV within the range of 2,000 h⁻¹ to 40,000 h⁻¹.

The term “thermal runaway” describes a process wherein the heat releasedby a catalyzed exothermic reaction (e.g., hydrogenation) increases thetemperature of the catalyst, which accelerates the catalyzed reactionrate. In turn, the amount of heat released by the accelerated reactionincreases, further increasing the catalyst temperature. The person ofordinary skill in the art will appreciate that, in the case of acetylenehydrogenation, this process of thermal runaway leads to increasedformation of ethane (C₂H₆). Accordingly, as used herein, the term“thermal runaway” describes a process in which at least 90% of theacetylene present in a process gas is hydrogenated, and no more than 1mol. % of the total acetylene and ethylene present in the process gas isconverted to ethane. That is, of the acetylene present in the processgas input to the method, at least 90% of it is hydrogenated. Ethyleneand acetylene are the typical components of process gases that can beover-reduced to form ethane; the present inventors have noted that theamount of this undesirable overreduction can be decreased through use ofthe catalysts and methods herein. Thus, “no more than 1 mol. % of thetotal acetylene and ethylene present in the process gas is converted toethane” means that the amount of ethane output from the process does notincrease by more than 1 mol. % based on the total content of the reactoroutput gas as compared to the input process gas. For example, if theinput process gas stream has 20 mol. % ethane, the output stream has nomore than 21 mol. % ethane.

As used herein, selectivity is defined as the portion of acetylene thatis converted to ethylene, i.e., (ethylene gain)/(acetylene lost).

Another aspect of the disclosure is a method for selectivelyhydrogenating acetylene, the method comprising contacting a catalystcomposition with a process gas at a GHSV of at least 7,100 h⁻¹ (e.g.,within the range of 7,500 h⁻¹ to 40,000 h⁻¹). GHSV values are determinedwith reference to the volume of the catalyst bed(s). The catalystcomposition comprises a porous support, palladium, and one or more ionicliquids. The process gas includes ethylene, present in the process gasin an amount of at least 15 mol %; acetylene, present in the process gasin an amount of at least 1 ppm; and hydrogen, present in the process gasin an amount of at least 2 mol. %. At least 90% of the acetylene presentin the process gas is hydrogenated, and the selective hydrogenation isconducted without thermal runaway (i.e., no more than 1 mol. % of thetotal of acetylene and ethylene present in the process gas is convertedto ethane). The present inventors have determined that the highselectivity of the catalysts described herein can allow for operation atunexpectedly high space volumes. In certain such embodiments, theprocess gas includes up to 20,000 ppm carbon monoxide.

The contacting of the process gas can be conducted using a variety ofequipment familiar to a person of ordinary skill in the art. Forexample, the catalyst composition may be contained in one bed within areactor vessel or divided up among a plurality of beds within a reactor.The reaction system may contain one or more reaction vessels in series.The feed to the reaction zone can flow vertically upwards, or downwardsthrough the catalyst bed in a typical plug flow reactor, or horizontallyacross the catalyst bed in a radial flow type reactor. The reactionvessels can be adiabatic reactors with inter coolers, or cooledreactors, e.g. tubular isothermal reactors where catalyst is in thetubes or cooling medium is in the tubes. In some embodiments, at least90% of the acetylene present in the process gas can be hydrogenated bycontacting a catalyst composition contained in one bed. In otherembodiments, at least 90% of the acetylene present in the process gascan be hydrogenated by contacting a catalyst composition divided upamong a plurality of beds. The process gas can be provided as a singlestream, or can be provided as multiple streams (e.g., a hydrogen streamand a hydrocarbon feed stream) that are combined in a reactor.

The present inventors have determined that, advantageously, the methodsas otherwise described herein can provide beneficial performance in, forexample, otherwise conventional olefin processing systems. For example,the methods as otherwise described herein can be conducted toselectively hydrogenate acetylene contained in a crude olefin streamproduced by cracking (i.e., a raw-gas hydrocarbon feed), or the overheadstream of a system for separating C₃ hydrocarbons (i.e., ade-propanizer) or C₂ hydrocarbons (i.e., a de-ethanizer) from an olefinstream. In another example, the methods as otherwise described hereincan be conducted to selectively hydrogenate acetylene contained in arefinery off-gas stream. Accordingly, in various embodiments asotherwise described herein, the process gas is provided from an effluentof a cracking process, from an overhead stream of a depropanizer, froman overhead stream of a de-ethanizer, or from a refinery off-gas stream.

In certain embodiments of the methods as otherwise described herein, theselective hydrogenation is conducted at a temperature within the rangeof 20° C. to 140° C. In certain desirable embodiments, the selectivehydrogenation is conducted at a temperature within the range of 40° C.to 100° C., e.g., 40° C. to 90° C., or 50° C. to 100° C., or 50° C. to90° C. But the processes can be conducted at a variety of temperatures.For example, in certain such embodiments, the selective hydrogenation isconducted at a temperature within the range of 20° C. to 130° C., e.g.,in the range of 20° C. to 120° C., or 20° C. to 110° C., or 20° C. to100° C., or 20° C. to 90° C. In other such embodiments, the selectivehydrogenation is conducted at a temperature within the range of 40° C.to 140° C., e.g., 40° C. to 130° C., or 40° C. to 120° C., or 40° C. to110° C. In other such embodiments, the selective hydrogenation isconducted at a temperature within the range of 50° C. to 140° C., e.g.,50° C. to 130° C., or 50° C. to 120° C., or 50° C. to 110° C. In othersuch embodiments, the selective hydrogenation is conducted at atemperature within the range of 60° C. to 140° C., e.g., 60° C. to 130°C., or 60° C. to 120° C., or 60° C. to 110° C., or 60° C. to 100° C., or60° C. to 90° C.

Advantageously, the present inventors have determined that the processgas of the methods as otherwise described herein can include carbonmonoxide (CO) in an amount within a relatively broad range. For example,the present inventors have noted that prior art processes typicallyinclude some amount of carbon monoxide in the process feed, going so faras to add carbon monoxide to process feeds that do not have sufficientcarbon monoxide. The purpose of the carbon monoxide is to mediate theactivity of the catalyst, so that the process does not run away andproduce more ethane than desired. Conventional catalysts were understoodto have lower selectivity for hydrogenation of acetylene, especially atlower carbon monoxide concentrations, and so addition of carbon monoxidewas understood to be desirable to maintain a relatively low amount ofethane in the process output. In contrast, the present inventors havedetermined that the catalysts described herein can provide highselectivity without runaway even at low CO concentrations. Accordingly,in certain embodiments of the methods as otherwise described herein, COis present in the process gas in an amount up to 190 ppm, e.g., withinthe range of 1 ppm to 190 ppm, for example, in the range of 5 ppm to 190ppm, or 10 ppm to 190 ppm, or 25 ppm to 190 ppm, or 50 ppm to 190 ppm,or 100 ppm to 190 ppm. In certain embodiments of the methods asotherwise described herein, CO is present in the process gas in anamount up to 180 ppm, e.g., within the range of 1 ppm to 180 ppm, forexample, in the range of 5 ppm to 180 ppm, or 10 ppm to 180 ppm, or 25ppm to 180 ppm, or 50 ppm to 180 ppm, or 100 ppm to 180 ppm. In certainembodiments of the methods as otherwise described herein, CO is presentin the process gas in an amount up to 170 ppm, e.g., within the range of1 ppm to 170 ppm, for example, in the range of 5 ppm to 170 ppm, or 10ppm to 170 ppm, or 25 ppm to 170 ppm, or 50 ppm to 170 ppm, or 100 ppmto 170 ppm. In certain embodiments of the methods as otherwise describedherein, CO is present in the process gas in an amount up to 160 ppm,e.g., within the range of 1 ppm to 160 ppm, for example, in the range of5 ppm to 160 ppm, or 10 ppm to 160 ppm, or 25 ppm to 160 ppm, or 50 ppmto 160 ppm, or 100 ppm to 160 ppm. In certain embodiments of the methodsas otherwise described herein, CO is present in the process gas in anamount up to 150 ppm, e.g., within the range of 1 ppm to 150 ppm, forexample, in the range of 5 ppm to 150 ppm, or 10 ppm to 150 ppm, or 25ppm to 150 ppm, or 50 ppm to 150 ppm, or 100 ppm to 150 ppm. In certainembodiments of the methods as otherwise described herein, CO is presentin the process gas in an amount up to 140 ppm, e.g., within the range of1 ppm to 140 ppm, for example, in the range of 5 ppm to 140 ppm, or 10ppm to 140 ppm, or 25 ppm to 140 ppm, or 50 ppm to 140 ppm, or 100 ppmto 140 ppm. In certain embodiments of the methods as otherwise describedherein, CO is present in the process gas in an amount up to 130 ppm,e.g., within the range of 1 ppm to 130 ppm, for example, in the range of5 ppm to 130 ppm, or 10 ppm to 130 ppm, or 25 ppm to 130 ppm, or 50 ppmto 130 ppm, or 100 ppm to 130 ppm. In certain embodiments of the methodsas otherwise described herein, CO is present in the process gas in anamount up to 120 ppm, e.g., within the range of 1 ppm to 120 ppm, forexample, in the range of 5 ppm to 120 ppm, or 10 ppm to 120 ppm, or 25ppm to 120 ppm, or 50 ppm to 120 ppm. In certain embodiments of themethods as otherwise described herein, CO is present in the process gasin an amount up to 110 ppm, e.g., within the range of 1 ppm to 110 ppm,for example, in the range of 5 ppm to 110 ppm, or 10 ppm to 110 ppm, or25 ppm to 110 ppm, or 50 ppm to 110 ppm. In certain embodiments of themethods as otherwise described herein, CO is present in the process gasin an amount up to 100 ppm, e.g., within the range of 1 ppm to 100 ppm,for example, in the range of 5 ppm to 100 ppm, or 10 ppm to 100 ppm, or25 ppm to 100 ppm, or 50 ppm to 100 ppm. In certain embodiments of themethods as otherwise described herein, CO is present in the process gasin an amount up to 90 ppm, e.g., within the range of 1 ppm to 90 ppm,for example, in the range of 5 ppm to 90 ppm, or 10 ppm to 90 ppm, or 25ppm to 90 ppm, or 50 ppm to 90 ppm. In certain embodiments of themethods as otherwise described herein, CO is present in the process gasin an amount up to 80 ppm, e.g., within the range of 1 ppm to 80 ppm,for example, in the range of 5 ppm to 80 ppm, or 10 ppm to 80 ppm, or 25ppm to 80 ppm, or 50 ppm to 80 ppm. In certain embodiments of themethods as otherwise described herein, CO is present in the process gasin an amount up to 50 ppm, e.g., within the range of 1 ppm to 50 ppm,for example, in the range of 5 ppm to 50 ppm, or 10 ppm to 50 ppm, or 25ppm to 50 ppm. In certain embodiments of the methods as otherwisedescribed herein, essentially no CO is present in the process gas.

Notably, in certain embodiments of the methods as otherwise describedherein, carbon monoxide is not added to a feed gas stream to provide theprocess gas. That is, unlike in many conventional methods, in certainembodiments as otherwise described herein there is no to maintain abaseline CO concentration in the process gas to maintain sufficientlylow exothermicity due to ethylene hydrogenation. Rather, the catalystsdescribed herein are highly selective to acetylene hydrogenation toethylene, even at low CO concentrations, and so there is little riskthermal runaway due to ethylene reduction at such low CO concentrations.

The present inventors have noted that a process gas high in CO canresult from variances in an upstream process step, and that continuedhydrogenation performance throughout and/or after such a variance wouldalso be desirable. The present inventors have noted that the catalystsdescribed herein can provide continued production without runaway ofin-specification gases for downstream process at high CO levels up to20000 ppm, even in view of the significantly higher temperatures thatsuch CO concentrations typically require (i.e., as compared to thetemperatures required to cleanup acetylene at low CO levels). Notably,as described in Example 7 below, the catalysts described herein can haverelatively invariant acetylene selectivity even at higher COconcentrations. In certain embodiments as otherwise described herein, COis present in the process gas in an amount of at least 600 ppm (e.g., atleast 800 ppm, or at least 1,000 ppm, or at least 1,500 ppm, or at least2,000 ppm). For example, in certain embodiments as otherwise describedherein, CO is present in the process gas in an amount within the rangeof 600 ppm to 20,000 ppm. For example, in certain such embodiments, COis present in the process gas in an amount within the range of 600 ppmto 15,000 ppm, or 600 ppm to 10,000 ppm, or 600 ppm to 5,000 ppm, or 600ppm to 2,500 ppm, or 600 ppm to 1,500 ppm, or 700 ppm to 1,200 ppm, or800 ppm to 1,200 ppm, or 900 ppm to 1,200 ppm, or 700 ppm to 1,000 ppm,or 800 ppm to 1,100 ppm. In other such embodiments, CO is present in theprocess gas in an amount in the range of 800 ppm to 20,000 ppm, or 800ppm to 15,000 ppm, or 800 ppm to 10,000 ppm, or 800 ppm to 5,000 ppm, or800 ppm to 2,500 ppm, or 800 ppm to 1,500 ppm. In other suchembodiments, CO is present in the process gas in an amount in the rangeof 1,000 ppm to 20,000 ppm, or 1,000 ppm to 15,000 ppm, or 1,000 ppm to10,000 ppm, or 1,000 ppm to 5,000 ppm, or 1,000 ppm to 2,500 ppm. Inother such embodiments, CO is present in the process gas in an amount inthe range of 1,500 ppm to 20,000 ppm, or 1,500 ppm to 15,000 ppm, or1,500 ppm to 10,000 ppm, or 1,500 ppm to 5,000 ppm. In other suchembodiments, CO is present in the process gas in an amount in the rangeof 2,000 ppm to 20,000 ppm, or 2,000 ppm to 15,000 ppm, or 2,000 ppm to10,000 ppm, or 2,000 ppm to 5,000 ppm.

However, in other embodiments, the process gas can have a different COconcentration. For example, in certain embodiments (e.g., when the GHSVis at least 7,500 h⁻¹, at least 10,000 h⁻¹, at least 15,000 h⁻¹ or atleast 20,000 h⁻¹), the CO concentration of the process gas is up to1,200 ppm, e.g., up to 1,000 ppm, or up to 500 ppm, or in the range of10 ppm to 1,200 ppm, or in the range of 10 ppm to 500 ppm, or in therange of 50 ppm to 1,200 ppm, or in the range of 50 ppm to 500 ppm, orin the range of 100 ppm to 1,200 ppm, or in the range of 100 ppm to 500ppm.

Advantageously, the present inventors have determined that the processgas of the methods as otherwise described herein can be contacted withthe catalyst composition at a relatively high rate (e.g., at least 7,100h⁻¹, or within the range of 7,500 h⁻¹ to 40,000 h⁻¹), desirablyincreasing throughput. The present inventors determined that as a resultof the high selectivity of the catalysts described herein;advantageously, the methods described herein can be run at highthroughput, while retaining selectivity and without causing runaway.Accordingly, the methods described herein can be conducted in aselective hydrogenation reactor (e.g., including a single catalyst bed,or a plurality of catalyst beds) having a relatively small volume (i.e.,as compared to conventional processes to achieve the same overall rateof formation of product). Accordingly, in certain embodiments asotherwise described herein, the process gas is contacted with thecatalyst at a GHSV of at least 7,100 h⁻¹, e.g., within the range of7,100 h⁻¹ to 40,000 h⁻¹, or 7,100 h⁻¹ to 30,000 h⁻¹, or 7,100 h⁻¹ to20,000 h⁻¹. In certain embodiments as otherwise described herein, theprocess gas is contacted with the catalyst at a GHSV of at least 7,500h⁻¹, e.g., within the range of 7,500 h⁻¹ to 40,000 h⁻¹, or 7,500 h⁻¹ to30,000 h⁻¹, or 7,500 h⁻¹ to 20,000 h⁻¹. In certain embodiments asotherwise described herein, the process gas is contacted with thecatalyst at a GHSV of at least 10,000 h⁻¹, e.g., within the range of10,000 h⁻¹ to 40,000 h⁻¹, or 10,000 h⁻¹ to 30,000 h⁻¹, or 10,000 h⁻¹ to20,000 h⁻¹. In certain embodiments as otherwise described herein, theprocess gas is contacted with the catalyst at a GHSV of at least 15,000h⁻¹, e.g., within the range of 15,000 h⁻¹ to 40,000 h⁻¹, or 15,000 h⁻¹to 30,000 h⁻¹, or 15,000 h⁻¹ to 20,000 h⁻¹. In certain embodiments asotherwise described herein, the process gas is contacted with thecatalyst at a GHSV of at least 20,000 h⁻¹, e.g., within the range of20,000 h⁻¹ to 40,000 h⁻¹, or 20,000 h⁻¹ to 30,000 h⁻¹. GHSV values aredetermined with reference to the total volume of the catalyst bed(s).

As noted above, the processes described herein are performed such thatat least 90% of the acetylene present in the process gas is hydrogenated(i.e., the acetylene conversion is at least 90%). For example, incertain embodiments of the methods as otherwise described herein, atleast 92.5%, or at least 95 mol. %, or at least 96%, or at least 97%, orat least 97.5%, or at least 98%, or at least 98.5%, or at least 99% ofthe acetylene present in the process gas is hydrogenated. In certainembodiments of the methods as otherwise described herein, essentiallyall of the acetylene present in the process gas is hydrogenated.

As noted above, in various aspects, the methods as otherwise describedherein can be performed without thermal runaway, i.e., no more than 1mol. % of the total of acetylene and ethylene present in the process gasis converted to ethane. For example, in certain embodiments of themethods as otherwise described herein, no more than 0.9 mol. %, or nomore than 0.8 mol. %, or no more than 0.7 mol. %, or no more than 0.6mol. %, or no more than 0.5 mol. % of the total of acetylene andethylene present in the process gas is converted to ethane (i.e., theamount of ethane output from the process does not increase by more than0.8 mol. %, or 0.7 mol. %, or 0.6 mol. %, or 0.5 mol. % based on thetotal content of the process gas as compared to the input process gas).For example, in certain embodiments of the methods as otherwisedescribed herein, no more than 0.2 mol. %, e.g., no more than 0.1 mol.%, or no more than 0.05 mol. %, of the total of acetylene and ethylenepresent in the process gas is converted to ethane. In certainembodiments of the methods as otherwise described herein, essentiallynone of the total of acetylene and ethylene present in the process gasis converted to ethane.

Put another way, the amount of ethane in the selectively hydrogenatedproduct of the methods as otherwise described herein can include anamount of ethane that is no more than 1 mol. % greater than the amountof ethane in the process gas (i.e., before contacting a catalystcomposition as otherwise described herein). For example, in certainembodiments, the amount of ethane in the selectively hydrogenatedproduct of a method as otherwise described herein is no more than 0.9mol. % greater, or no more than 0.8 mol. % greater, or no more than 0.7mol. % greater, or no more than 0.6 mol. % greater, or no more than 0.5mol. % greater than the amount of ethane in the process gas. In certainembodiments, the amount of ethane in the selectively hydrogenatedproduct of a method as otherwise described herein is no more than 0.2mol. % greater, e.g., no more than 0.1 mol. % greater, or no more than0.05 mol. % than the amount of ethane in the process gas. In certainembodiments, the amount of ethane in the selectively hydrogenatedproduct of a method as otherwise described herein is essentially thesame as the amount of ethane in the process gas.

As described above, a wide variety of process gases can be treated usingthe selective hydrogenation methods described herein. For example, incertain embodiments of the methods as otherwise described herein,ethylene is present in the process gas in an amount of at least 15 mol.%. For example, in certain such embodiments, ethylene is present in theprocess gas in an amount in the range of 15 mol. % to 70 mol. %, or 15mol. % to 60 mol. %, or 15 mol. % to 50 mol. %. In certain embodimentsas otherwise described herein, ethylene is present in the process gas inan amount of at least 20 mol. %, e.g., in the range of 20 mol. % to 70mol. %, or 20 mol. % to 60 mol. %, or 20 mol. % to 50 mol. %. In certainembodiments as otherwise described herein, ethylene is present in theprocess gas in an amount of at least 30 mol. %, e.g., in the range of 30mol. % to 70 mol. %, or 30 mol. % to 60 mol. %, or 30 mol. % to 50 mol.%.

Acetylene can be present in the process gas composition in a variety ofamounts, depending on the particular source of the process gas. Incertain embodiments of the methods as otherwise described herein,acetylene is present in the process gas in an amount of at least 10 ppm,at least 50 ppm, at least 100 ppm, or at least 500 ppm, e.g., in anamount in the range of 10 ppm to 2 mol. %, or 10 ppm to 1 mol. %, or 10ppm to 0.5 mol %, or 50 ppm to 2 mol. %, or 50 ppm to 1 mol. %, or 50ppm to 0.5 mol %, or 100 ppm to 2 mol. %, or 100 ppm to 1 mol. %, or 100ppm to 0.5 mol. %, or 500 ppm to 2 mol. %, or 500 ppm to 1 mol. %, or500 ppm to 0.5 mol. %. In certain embodiments of the methods asotherwise described herein, acetylene is present in the process gas inan amount of at least 0.1 mol. %, e.g., at least 0.5 mol. % or at least1 mol. %, e.g., in the range of 0.1 mol. % to 2 mol. %, or 0.5 mol. % to2 mol. %, or 1 mol. % to 2 mol. %, or 0.1 mol. % to 1.5 mol. %, or 0.5mol. % to 1.5 mol. %, or 1 mol. % to 1.5 mol. %, or 0.1 mol. % to 1 mol.%, or 0.5 mol. % to 1 mol. %.

Hydrogen can be provided in the process gas at a variety ofconcentrations. The person of ordinary skill in the art will select anamount of hydrogen that provides the necessary reduction of acetylene,and, for example, to provide the desired amount of hydrogen for asubsequent process step. In certain embodiments as otherwise describedherein, the hydrogen is present in the process gas in an amount of atleast 5 mol. %, at least 6 mol. %, at least 7 mol. %, at least 8 mol. %,at least 9 mol. %, or at least 10 mol. %, for example, in the range of 5mol. % to 50 mol. %, or 5 mol. % to 35 mol. %, or 5 mol. % to 20 mol. %,or 5 mol. % to 15 mol. %, or 8 mol. % to 50 mol. %, or 8 mol. % to 35mol. %, or 8 mol. % to 20 mol. %, or 8 mol. % to 15 mol. %, or 10 mol. %to 50 mol. %, or 10 mol. % to 35 mol. %, or 10 mol. % to 20 mol. %, or10 mol. % to 15 mol. %.

The person of ordinary skill in the art will appreciate that othercomponents may be present in the process gas of the methods as otherwisedescribed herein. For example, the process gas can include one or morecomponents typically present in a crude olefin stream produced bycracking such as, for example, C₁ components (e.g., including methane,carbon monoxide, and carbon dioxide), C₂ components (e.g., includingethylene, ethane, and acetylene), and C₃ components (e.g., includingpropane, propylene, propadiene, and methyl acetylene), and C₄ components(e.g., including 1,3-butadiene). However, in certain embodiments, theprocess gas will contain no more than 10 mol. % (e.g., no more than 5mol. %, no more than 2 mol. % or no more than 1 mol. %) ofcarbon-containing components other than C₁ components (e.g., methane,carbon monoxide, and carbon dioxide), C₂ components (e.g., ethylene,ethane, and acetylene), and C₃ components (e.g., propylene, propane,methyl acetylene, and propadiene). In certain embodiments, the processgas will contain no more than 20 mol. % (e.g., no more than 15 mol. %,no more than 10 mol. % or no more than 5 mol. %) of carbon-containingcomponents other than ethylene, ethane, acetylene, carbon monoxide andcarbon dioxide. And in certain embodiments, the process gas will containno more than 5 mol. % (e.g., no more than 2 mol. %) of carbon-containingcomponents other than ethylene, ethane, acetylene, carbon monoxide andcarbon dioxide.

Various gas streams can be combined to provide the process gas. Forexample, a hydrogen-containing gas stream can be added to another gasstream to provide the process gas. Gas streams can be combined in thereactor to provide the process gas that is the combination of the inputgas streams.

As noted above, in various aspects, the methods of the disclosurecomprise contacting a catalyst composition with a process gas.Accordingly, another aspect of the disclosure is a catalyst compositioncomprising a porous support, palladium, and one or more ionic liquids.In certain embodiments as otherwise described herein, the catalystcomposition comprises a porous support selected from alumina, silica,titania, and any mixture thereof. In certain such embodiments, thealumina, silica, titania, and any mixture thereof are present in thecatalyst composition in a total amount within the range of 90 wt. % to99.9 wt. %, calculated as oxide on a calcined basis. For example, incertain embodiments as otherwise described herein, the catalystcomposition comprises a porous support selected from alumina, silica,titania, and any mixture thereof, present in the catalyst composition inan amount within the range of 92.5 wt. % to 99 wt. %, or 95 wt. % to99.9 wt. %, or 97.5 wt. % to 99.9 wt. %. In certain such embodiments,the porous support is a mixture of alumina and silica. In other suchembodiments, the porous support is alumina, e.g., alpha-alumina.

As used herein, the term “oxide,” including, e.g., “mixed oxide,”“alumina,” “silica,” etc., includes oxides in all forms and crystallinephases. For example, “alumina” includes Al₂O₃, Al₂Ox wherein x is withinthe range of 1 to 3, etc. Unless otherwise indicated, regardless of theactual stoichiometry of the oxide, oxides are calculated as the moststable oxide for purposes of weight percent determinations. For example,the person of ordinary skill in the art will appreciate that anon-stoichiometric oxide of aluminum, or even another form of aluminum,may still be calculated as Al₂O₃. Moreover, unless otherwise indicated,the compositions are described on an as-calcined basis.

In certain embodiments as otherwise described herein, the BET surfacearea of the porous support is within the range of 2 m²/g to 10 m²/g. Theperson of ordinary skill in the art will appreciate that the “BETsurface area” of a material refers to the specific surface area of amaterial, and is determined through the standardized testing procedureASTM D3663 (“Standard Test Method for Surface Area of Catalysts andCatalyst Carriers”). For example, in certain embodiments as otherwisedescribed herein, the BET surface area of the porous support is withinthe range of 2 m²/g to 9 m²/g, or 2 m²/g to 8 m²/g, or 2 m²/g to 7 m²/g,or 2 m²/g to 6 m²/g, or 2 m²/g to 5 m²/g, or 3 m²/g to 10 m²/g, or 4m²/g to 10 m²/g, or 5 m²/g to 10 m²/g, or 6 m²/g to 10 m²/g, or 2 m²/gto 6 m²/g, or 3 m²/g to 7 m²/g, or 4 m²/g to 8 m²/g, or 5 m²/g to 9m²/g. BET surface areas of no more than 10 m²/g can be provided bycalcining the support to a relatively high degree.

In certain embodiments as otherwise described herein, the pore volume(determined using mercury intrusion porisometry according to ASTM D4284)of the porous support is at least 0.10 mL/g, e.g., within the range of0.10 mL/g to 1.0 mL/g. For example, in certain embodiments as otherwisedescribed herein, the pore volume of the porous support (determinedusing mercury intrusion porisometry according to ASTM D4284) is withinthe range of 0.10 mL/g to 0.80 mL/g, or 0.20 mL/g to 0.80 mL/g, or 0.30mL/g to 0.80 mL/g, or 0.20 mL/g to 0.70 mL/g, or 0.30 mL/g to 0.70 mL/g.

The metal-impregnated porous support (i.e., including the poroussupport, the palladium and any promoters present, but not the ionicliquid) can similarly have a relatively high surface area, e.g., atleast of 0.10 mL/g (determined using mercury intrusion porisometryaccording to ASTM D4284). For example, in certain embodiments asotherwise described herein, the metal-impregnated porous support has apore volume of at least at least 0.15 mL/g, at least 0.20 mL/g, or even0.25 mL/g. In various embodiments as otherwise described herein, themetal-impregnated porous support has a pore volume in the range of 0.10mL/g to 1.0 mL/g, e.g., 0.10 mL/g to 0.80 mL/g, or 0.10 to 0.60 mL/g, or0.10 to 0.40 mL/g, or 0.10 to 0.30 mL/g. In other embodiments asotherwise described herein, the metal-impregnated porous support has apore volume in the range of 0.15 mL/g to 1.0 mL/g, e.g., 0.15 mL/g to0.80 mL/g, or 0.15 to 0.60 mL/g, or 0.15 to 0.40 mL/g, or 0.15 to 0.30mL/g. In other embodiments as otherwise described herein, themetal-impregnated porous support has a pore volume in the range of 0.20mL/g to 1.0 mL/g, e.g., 0.20 mL/g to 0.80 mL/g, or 0.20 to 0.60 mL/g, or0.20 to 0.40 mL/g, or 0.20 to 0.35 mL/g. In other embodiments asotherwise described herein, the metal-impregnated porous support has apore volume in the range of 0.25 mL/g to 1.0 mL/g, e.g., 0.25 mL/g to0.80 mL/g, or 0.25 to 0.60 mL/g, or 0.25 to 0.40 mL/g, or 0.20 to 0.35mL/g.

The present inventors have determined certain advantages when themetal-impregnated porous support also has a relatively BET low surfacearea (i.e., no more than 10 m²/g, or a more particular range describedabove) together with high pore volume. Notably, in certain embodimentsas otherwise described herein, the porous support has a relatively lowBET surface area (i.e., no more than 10 m²/g, or a more particular rangedescribed above) but a relatively high pore volume (i.e., in excess of0.10 mL/g, e.g., within the range of 0.10 mL/g to 1.0 mL/g or a moreparticular range described above). This can allow for the material,after impregnation with ionic liquid as described herein, to retain somepore volume even in the presence of the ionic liquid.

For example, in certain embodiments as otherwise described herein, thecatalyst composition (i.e., including the porous support, the palladiumand any promoters present, and the ionic liquid) itself has a relativelyhigh pore volume (determined using mercury intrusion porisometryaccording to ASTM D4284) of at least 0.05 mL/g. In certain embodimentsas otherwise described herein, the catalyst composition has a porevolume of at least 0.10 mL/g, at least 0.15 mL/g, or even 0.20 mL/g. Invarious embodiments as otherwise described herein, the catalystcomposition has a pore volume in the range of 0.05 mL/g to 1.0 mL/g,e.g., 0.05 mL/g to 0.80 mL/g, or 0.05 to 0.60 mL/g, or 0.05 to 0.40mL/g, or 0.05 to 0.30 mL/g. In other embodiments as otherwise describedherein, the catalyst composition has a pore volume in the range of 0.10mL/g to 1.0 mL/g, e.g., 0.10 mL/g to 0.80 mL/g, or 0.10 to 0.60 mL/g, or0.10 to 0.40 mL/g, or 0.10 to 0.30 mL/g. In other embodiments asotherwise described herein, the catalyst composition has a pore volumein the range of 0.10 mL/g to 1.0 mL/g, e.g., 0.10 mL/g to 0.80 mL/g, or0.10 to 0.60 mL/g, or 0.10 to 0.40 mL/g, or 0.10 to 0.30 mL/g. In otherembodiments as otherwise described herein, the catalyst composition hasa pore volume in the range of 0.15 mL/g to 1.0 mL/g, e.g., 0.15 mL/g to0.80 mL/g, or 0.15 to 0.60 mL/g, or 0.15 to 0.40 mL/g, or 0.15 to 0.30mL/g. In other embodiments as otherwise described herein, the catalystcomposition has a pore volume in the range of 0.20 mL/g to 1.0 mL/g,e.g., 0.20 mL/g to 0.80 mL/g, or 0.20 to 0.60 mL/g, or 0.20 to 0.40mL/g, or 0.20 to 0.35 mL/g. Such materials can be provided by using arelatively low amount of ionic liquid, e.g., up to 4 wt. % or up to 3wt. %, depending on the pore volume of the support.

In certain embodiments as otherwise described herein, the catalystcomposition comprises palladium in an amount of at least 0.02 wt. %(i.e., calculated on an elemental mass basis). For example, in certainsuch embodiments, the catalyst composition comprises palladium in anamount of at least 0.03 wt. %, or at least 0.04 wt. %, or at least 0.05wt. %, or at least 0.06 wt. %, or at least 0.07 wt. %, or at least 0.08wt. %, or at least 0.09 wt. %, or at least 0.1 wt. %, or at least 0.11wt. %, or at least 0.12 wt. %, or at least 0.13 wt. %, or at least 0.14wt. %, or at least 0.15 wt. %. In certain such embodiments, the catalystcomposition comprises palladium in an amount of no more than 0.5 wt. %(e.g., no more than 0.4 wt. %, or no more than 0.3 wt. %, or no morethan 0.2 wt. %). For example, in certain embodiments as otherwisedescribed herein, the catalyst composition comprises palladium in anamount within the range of 0.02 wt. % to 0.5 wt. %, or 0.02 wt. % to0.45 wt. %, or 0.03 wt. % to 0.4 wt. %, or 0.03 wt. % to 0.35 wt. %, or0.04 wt. % to 0.3 wt. %, or 0.04 wt. % to 0.25 wt. %.

In certain embodiments as otherwise described herein, palladium islocalized at the surface of the support, in a so-called shell catalystconfiguration. Materials “localized at a surface” have a substantiallyhigher concentration (e.g., at least 100% higher) at the surface of thematerial (including a surface of an internal pore) than in the interiorof the material. The person of ordinary skill in the art will furtherappreciate that the “surface” of a composition does not consist solelyof the outermost surface of atoms of a composition, but rather includesa surface layer at the outside of the composition. For example, thepalladium-containing shell on the support can, in certain embodiments,have a thickness up to 1 mm. The thickness of the shell is, in certainembodiments as otherwise described herein, in the range of 100-800 μm.

In certain embodiments as otherwise described herein, the catalystcomposition further comprises at least one promoter selected fromsilver, gold, zinc, tin, lead, gallium, cadmium, copper, bismuth,sodium, cesium, or potassium. For example, in certain such embodiments,the catalyst composition comprises a silver promoter. In other suchembodiments, the catalyst composition comprises a gold or zinc promoter.In certain embodiments as otherwise described herein, the at least onepromoter (e.g., silver) is present in the catalyst composition in atotal amount of at least 0.02 wt. % (i.e., calculated on an elementalmass basis), or least 0.04 wt. %, or at least 0.06 wt. %, or at least0.08 wt. %, or at least 0.1 wt. % or at least 0.12 wt. %, or at least0.14 wt. %, or at least 0.16 wt. %, or at least 0.18 wt. %, or at least0.2 wt. %, or at least 0.22 wt. %, or at least 0.24 wt. %, or at least0.26 wt. %, or at least 0.28 wt. %, or at least 0.3 wt. %. In certainsuch embodiments, the catalyst composition comprises the at least onepromoter in a total amount of no more than 0.6 wt. % (e.g., no more than0.45 wt. %, or no more than 0.3 wt. %). In certain embodiments asotherwise described herein, the at least one promoter (e.g., silver) ispresent together with the palladium in a shell layer. In certainembodiments, the mass ratio of palladium to promoter metal lies within arange of 1:5 to 3:1, e.g., within a range of 1:4 to 2:1, or within arange of 1:3 to 1:1.

In certain embodiments as otherwise described herein, the catalystcomposition comprises at least one ionic liquid in a total amount up to10 wt. %. For example, in certain embodiments as otherwise describedherein, the catalyst composition comprises at least one ionic liquid ina total amount within the range of 0.01 wt. % to 10 wt. %, e.g., 0.01wt. % to 8 wt. %, or 0.01 wt. % to 6 wt. %, or 0.01 wt. % to 4 wt. %, or0.01 wt. % to 3 wt. %, or 0.01 wt. % to 2 wt. %, or 0.01 wt. % to 1 wt.%. In certain embodiments as otherwise described herein, the ionicliquid is present in an amount in the range of 0.05 wt. % to 10 wt. %,e.g., 0.05 wt. % to 8 wt. %, or 0.05 wt. % to 6 wt. %, or 0.05 wt. % to4 wt. %, or 0.05 wt. % to 3 wt. %, or 0.05 wt. % to 2 wt. %, or 0.05 wt.% to 1 wt. %. In certain embodiments as otherwise described herein, thecatalyst composition comprises at least one ionic liquid in a totalamount within the range of 0.1 wt. % to 10 wt. %, e.g., 0.1 wt. % to 8wt. %, or 0.1 wt. % to 6 wt. %, or 0.1 wt. % to 4 wt. %, or 0.1 wt. % to3 wt. %, or 0.1 wt. % to 2 wt. %, or 0.1 wt. % to 1 wt. %. In certainembodiments as otherwise described herein, the catalyst compositioncomprises at least one ionic liquid in a total amount within the rangeof 0.2 wt. % to 10 wt. %, e.g., 0.2 wt. % to 8 wt. %, or 0.2 wt. % to 6wt. %, or 0.2 wt. % to 4 wt. %, or 0.2 wt. % to 3 wt. %, or 0.2 wt. % to2 wt. %, or 0.2 wt. % to 1 wt. %. In certain embodiments as otherwisedescribed herein, the catalyst composition comprises at least one ionicliquid in a total amount within the range of 0.5 wt. % to 10 wt. %,e.g., 0.5 wt. % to 8 wt. %, or 0.5 wt. % to 6 wt. %, or 0.5 wt. % to 4wt. %, or 0.5 wt. % to 3 wt. %, or 0.5 wt. % to 2 wt. %.

The person of ordinary skill in the art will appreciate that the term“ionic liquid” refers generally to the class of poorly coordinated saltshaving a relatively low melting point such as, for example, less than100° C. In certain embodiments as otherwise described herein, the ionicliquid comprises a compound of the formula:[A]_(n) ⁺[Y]_(n) ⁻wherein n is 1 or 2;

[Y]_(n) ⁻ is selected from tetrafluoroborate ([BF₄]⁻)hexafluorophosphate ([PF₆]⁻); dicyanamide ([N(CN)₂]⁻); halides (Cl⁻,Br⁻, F⁻, I⁻); hexafluoroantimonate ([SbF₆]⁻); nitrate ([NO₃]⁻); nitrite([NO₂]⁻); anionic metal complexes (e.g., [CuCl₄]₂ ⁻, [PdCl₄]₂ ⁻,[AuCl₄]⁻); acetate ([CH₃COO]⁻); trifluoracetate ([F₃CCOO]⁻);hexafluoroarsenate ([AsF₆]⁻); sulfate ([SO₄]₂ ⁻; hydrogen sulfate([R′—SO₄]⁻); alkyl sulfate ([R′—SO4]⁻); tosylate ([C₇H₇SO₃]⁻); triflate([CF₃SO₃]⁻); nonaflate ([C₄F₉SO₃]⁻); triperfluoroethylenetrifluorophosphate ([PF₃(C₂F₅)₃]⁻); tricyanomethide ([C(CN)₃]⁻);tetracyanoborate ([B(CN)₄]⁻; thiocyanate ([SCN]⁻); carbonate ([CO₃]₂);carboxylate ([R′—COO]⁻); sulfonate ([R′SO₃]⁻); dialkylphosphate([R′PO₄R″]⁻); alkyl phosphonate ([R′HPO₃]⁻); and bissulfonylimide([(R′—SO₂)₂N]⁻) (e.g., bis(trifluormethylsulfonyl)imide); wherein R′ andR″ are each independently linear or branched C₁-C₁₂ aliphatic oralicyclic alkyl; C₅-C₁₈ aryl; C₅-C₁₈ aryl-substituted C₁-C₆ alkyl; orC₁-C₆ alkyl-substituted C₅-C₁₈ aryl, the alkyl optionally substitutedwith one or more halogens;

[A]⁺ is selected from quaternary ammonium cations having the formula[NR¹R²R³R]⁺, phosphonium cations having the formula [PR¹R²R³R]⁺,sulfonium cations having the formula [SR¹R²R]+, guanidinium cationshaving the formula:

imidazolium cations having the formula:

wherein the imidazole is optionally substituted with one or more groupsselected from C₁-C₆ alkyl; C₁-C₆ alkoxy; C₁-C₆ aminoalkyl; C₅-C₁₂ aryl;and C₅-C₁₂ aryl-substituted C₁-C₆ alkyl; pyridinium cations having theformula:

wherein the pyridine is optionally substituted with one or more groupsselected from C₁-C₆ alkyl; C₁-C₆ alkoxy; C₁-C₆ aminoalkyl; C₅-C₁₂ aryl;and C₅-C₁₂ aryl-substituted C₁-C₆ alkyl; pyrazolium cations having theformula:

wherein the pyrazole is optionally substituted with one or more groupsselected from C₁-C₆ alkyl; C₁-C₆ alkoxy; C₁-C₆ aminoalkyl; C₅-C₁₂ aryl;and C₅-C₁₂ aryl-substituted C₁-C₆ alkyl; and triazolium cations havingthe formula:

wherein the triazole is optionally substituted with one or more groupsselected from C₁-C₆ alkyl; C₁-C₆ alkoxy; C₁-C₆ aminoalkyl; C₅-C₁₂ aryl;and C₅-C₁₂ aryl-substituted C₁-C₆ alkyl; wherein R¹, R², R³ are eachindependently hydrogen; C₁-C₂₀ alkyl; C₃-C₈ heteroaryl optionallysubstituted with one or more of C₁-C₆ alkyl and halogen; C₃-C₆heteroaryl-substituted C₁-C₆ alkyl, the heteroaryl optionallysubstituted with one or more of C₁-C₆ alkyl and halogen; a polyetherhaving the formula [—CH₂CH₂O]_(n)R^(a) wherein n is within the range of1-50,000 and R^(a) is selected from C₁-C₂₀ alkyl; C₅-C₁₂ aryl optionallysubstituted with one or more of C₁-C₆ alkyl and halogen; and C₅-C₁₂aryl-substituted C₁-C₆ alkyl, the aryl optionally substituted with oneor more of C₁-C₆ alkyl and halogen; and wherein R is selected fromC₁-C₂₀ alkyl; C₄-C₈ heteroaryl-substituted C₁-C₆ alkyl, the heteroaryloptionally substituted with one or more of C₁-C₆ alkyl and halogen; andC₄-C₁₂ aryl-substituted C₁-C₆ alkyl, the aryl optionally substitutedwith one or more of C₁-C₆ alkyl and halogen.

For example, in certain such embodiments, [A]_(n) ⁺ is selected from1-butyl-1-methylpyrrolidinium, 1-butyl-2,3-dimethylimidazolium,1-butyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium,1-ethyl-3-methylpyridinium, 1-methyl-3-octylimidazolium,ethyldimethyl-(2-methoxyethyl)ammonium, tributylmethylammonium,tricyclohexyltetradecylphosphonium. In certain such embodiments, [Y]_(n)⁻ is selected from bis(trifluoromethylsulfonyl)imide, dicyanamide,ethylsulfate, methylphosphonate, methylsulfate, octylsulfate,tetracyanoborate, tetrafluoroborate, tricyanomethane, triflate, andtris(pentafluoroethyl)trifluorophosphate.

In certain embodiments as otherwise described herein, the at least oneionic liquid is selected from 1-butyl-3-methylimidazolium triflate,1-ethyl-3-methylpyridinium ethylsulfate, 1-butyl-1-methylpyrrolidiniumtriflate, 1-butyl-2,3-dimethylimidazolium triflate,1-butyl-3-methylimidazolium tricyanomethane, 1-butyl-3-methylimidazoliummethylsulfate, 1-butyl-3-methylimidazolium octylsulfate,1-butyl-3-methylimidazolium tetrafluoroborate,1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazoliummethylphosphonate, 1-ethyl-3-methylimidazolium triflate,1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide,1-butyl-1-methylpyrrolidinium tetracyanoborate,1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide,1-butyl-3-methylimidazolium tricyanomethane, 1-ethyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoliumtetracyanoborate, 1-ethyl-3-methylimidazoliumtris(pentafluoroethyl)trifluorophosphate, 1-methyl-3-octylimidazoliumtriflate, ethyldimethyl-(2-methoxyethyl)ammoniumtris(pentafluoroethyl)trifluorophosphate, tributylmethylammoniumdicyanamide, tricyclohexyltetradecylphosphoniumtris(pentafluoroethyl)trifluorophosphate, and1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

The person of ordinary skill in the art will appreciate that othercomponents may be present in the catalyst composition as otherwisedescribed herein. However, in certain embodiments as otherwise describedherein, the total amount of porous support, palladium, promoters, andionic liquid is at least 90 wt. %, or at least 92.5 wt. %, or at least95 wt. %, or at least 97.5 wt. %, or at least 98 wt. %, or at least 99wt. %, or at least 99.5 wt. %, or at least 99.9 wt. % of the catalystcomposition.

The person of ordinary skill in the art will appreciate that thecatalyst composition as otherwise described herein can be provided usingconventional methods, e.g., by one or more impregnation steps comprisingimpregnating (e.g., by incipient wetness or excess solution soaking) aporous support with an impregnation solution comprising one or moreionic liquids or palladium and, optionally, a promoter (e.g., silver),each impregnation step followed by a drying or calcining step.

In certain embodiments of the production of catalyst compositionsdescribed herein, the ionic liquid or mixtures of several ionic liquidsare dissolved or suspended in a solution agent suitable for the purpose,such as for example water, alcohols, acetone etc., or in a solutionagent mixture, and applied continuously onto the already pre-formedcatalyst inside a reaction chamber with the aid of a nozzle. For thisthe solution agent is continuously removed from the reaction chamberduring the process. In order to achieve an even coating of thesubstrate, the substrate material is continuously fluidized through aprocess gas in a process known as fluidized bed coating. Furthersuitable coating processes are dip coating or spray application with aspray pistol or a spray drying pistol.

Apart from the application of ionic liquid by means of coatingtechnologies, the same can also be applied by impregnating with asolution or suspension. For this the ionic liquid or mixtures of severalionic liquids are dissolved or suspended in a suitable solution agent(mixture) and subsequently brought into contact with the pre-formedcatalyst. The solution agent is then removed under vacuum or at anincreased temperature (or both), by resting in air, or by means of a gasstream. The quantity of solution agent used can be equal to or smalleror greater than the pore volume of the catalyst used.

The quantity of ionic liquid used is, in certain desirable embodiments,equal to or smaller than the pore volume of the catalyst used. After theapplication of the ionic liquid, one is left with an externally drysolid body coated with the desired quantity of ionic liquid. The porevolume of the resulting catalyst composition is reduced by the volume ofthe ionic liquid. Related to the total weight of the catalyst 0.1-10 wt.%, preferably 0.2-6 wt. %, and particularly preferably 0.3-4 wt. % ofionic liquid is used. The distribution of ionic liquid on themacroscopic substrate form body, granulate or powder is freelyadjustable by selecting the coating conditions. Depending on theselection of the conditions, a formation of a so-called eggshell,egg-white, egg-yolk, or a uniform distribution of the ionic liquid mayresult on the substrate. In addition, any concentration gradient ofionic liquid can be created on the substrate. The ionic liquid ispreferably applied to the substrate surface as a thin shell. The shellthickness of the ionic liquid on the substrate surface of the catalystsdescribed herein usually lies within a range of 10 to 2000 μm,preferably within a range of 100 to 1000 μm, and particularly preferablywithin a range of 100 to 800 μm.

The resulting catalyst can be used without restricting the targetreaction. The reduction of metal particles required for activating thecatalyst can either take place prior to a coating with the ionic liquidor following the same.

The catalyst can for example be reduced, before or after the addition ofthe ionic liquid or a mixture of ionic liquids. The methods to be usedfor reduction are known to the expert, and can for example include wetchemical methods through a reducing agent such as for example NaBH₄,LiAlH₄, hydrazine (hydrate), hypophosphite, formic acid, or salts of thesame (formates). In addition a reduction can be brought about in thegaseous phase with hydrogen (pure hydrogen or in a mixture containinghydrogen; preferably hydrogen concentration is higher than 1 mol. % inN₂ or other inert gases) within a temperature range of 20-200° C.,preferably at 50-150° C.

The reduced metal particles obtained in this way usually have a diameterwithin a range of 1 to 60 nm, preferably within a range of 1 to 30 nm,and particularly preferably within a range of 2 to 20 nm.

Similarly, the hydrogenation catalyst can be reduced after the ionicliquid is provided thereon, e.g., while in a bed in a reactor, bycontact with a hydrogen-containing gas as described above. For example,the ionic liquid can be impregnated onto the catalyst in a process at acatalyst synthesis site, then the catalyst can be shipped to and storedat the process site, with reduction being performed in the catalyst bedin the acetylene reduction reactor.

However, in other embodiments, the hydrogenation catalyst is notpre-reduced before contact with the process gas.

Before use, it can be advantageous to dry the catalyst to reduce theamount of any adsorbed water. Drying can be performed using a dry inertgas (e.g., nitrogen, hydrogen, residue methane, ethane) at a temperature(e.g., at at least 50° C., e.g., in the range of 50-100° C.) and for atime period (e.g., five hours to two days) until the drying gas effluentfalls below a desired dew point, e.g., less than −60° C.

After any hydrogenation and drying steps, it is desirable to reduce thetemperature of the catalyst to a first temperature for startup ofreactive gas flow. The present inventors have determined that thecatalysts described herein, as a result of their high selectivity toacetylene (and thus relatively low rate of reduction of ethylene), canbe started up at a relatively higher temperature. Conventional catalysts(like Catalyst C of the Examples) were typically started up at lowtemperature, 30° C. or less. Notably, the present inventors havedetermined that the catalysts described herein can be first contactedwith process gas at higher temperatures, e.g., in the range of 31-50° C.In certain embodiments, the catalysts described herein can first becontacted with process gas at a temperature in the range of 31-45° C.,or 31-40° C. In other such embodiments, the catalysts described hereincan first be contacted with process gas at a temperature in the range of35-50° C., e.g., 35-45° C., or 35-40° C. And in other such embodiments,the catalysts described herein can first be contacted with process gasat a temperature in the range of 40-50° C., e.g., 40-45° C., 31-40° C.,or in the range of 35-40° C.

Certain suitable catalysts for use in the methods described herein aredescribed in U.S. Patent Application Publication no. 2013/0102819, whichis hereby incorporated herein by reference in its entirety.

In various aspects and embodiments, the methods as otherwise describedherein can be conducted in a selective hydrogenation reactor housing acatalyst bed or a series of catalyst beds containing a catalystcomposition (e.g., a catalyst composition as otherwise described herein)capable of selectively hydrogenating acetylene.

In another aspect, the present inventors have determined that front endselective hydrogenation reactors can be started up without many of theundesirable aspects of conventional methods (e.g., long periods of timeof sending process gas to flare, pre-charging of the catalyst with CO,or addition of CO to the process stream during startup), even when thecatalyst composition is “fresh” (e.g., freshly installed or regeneratedin the reactor, reduced or non-reduced, not yet having been exposed to aprocess gas). As will be appreciated by the person of ordinary skill inthe art, such a startup process can desirably decrease material costs,decreases the down-time of the reactor, and decreases the waste outputof the reactor (i.e., the reactor output before the reactor is fullyoperational).

Accordingly, another aspect of the disclosure is a method for startingup a dehydrogenation reactor, the reactor housing one or more catalystbeds each containing a catalyst suitable for selectively hydrogenatingacetylene in a process gas comprising at least 10 mol. % ethylene, atleast 1 ppm acetylene, and at least 5 mol. % hydrogen (e.g., and atleast 10 ppm CO). The method includes providing each catalyst bed at nomore than a first temperature, the catalyst of the catalyst bed being incontact with a first gas, the first gas being non-reactive in thepresence of the catalyst at the first temperature. In the presence ofthe first gas, each catalyst bed is heated the catalyst bed to at leasta second temperature, the second temperature being at least 10 degreesgreater (e.g., at least 20 degrees greater, at least 30 degrees greater,at least 40 degrees greater, at least 50 degrees greater, or even atleast 60 degrees greater) than the first temperature, the first gasbeing non-reactive in the presence of the catalyst at the secondtemperature. The composition of the gas in contact with the catalyst ineach bed is changed from the first gas to a flow of the process gaswhile the catalyst bed is at least at the second temperature. Theprocess gas is allowed to flow through each catalyst bed until aconcentration of acetylene at an outlet of the reactor (i.e., thatserves as the outlet for the reacted process gas) is less than 1 ppm(e.g., less than 0.5 ppm). Thus, the temperature of the catalyst bed canbe increased while in contact with the first gas, such that process gasneed not be diverted to flare while the catalyst beds come totemperature. In certain embodiments, the concentration of acetylene atan outlet of the reactor is no more than 1 ppm within 6 hours, e.g.,within 5 hours, within 4 hours, within 3 hours or even within two hoursof the process gas being introduced to the one or more catalyst beds.The catalyst materials described herein can allow for introduction ofprocess gas while the catalyst bed(s) are at an elevated temperature,and thus reduce the amount of process gas flowing through the catalystbed(s) during startup.

In another aspect (in combination with the aspect described above orseparately), the disclosure provides a method for starting up aselective hydrogenation reactor without pre-treating the catalyst withCO and without adding CO to the process gas. For example, in oneembodiment, a method of starting up a selective hydrogenation reactor asdescribed above includes providing the reactor with each catalyst bedhaving its catalyst in contact with a first gas, the first gas beingnon-reactive in the presence of the catalyst at the first temperature,wherein the catalyst has not been contacted in the reactor with a carbonmonoxide-containing gas having a carbon monoxide concentration in excessof 100 ppm. A flow of the process gas is then introduced to the one ormore catalyst beds. Critically, the method includes refraining fromadding carbon monoxide to the process gas. Accordingly, the method isperformed without adding significant amounts of CO to the process (i.e.,through a pre-treatment or by addition to the process gas). The presentinventors have determined that use of the catalysts described herein canallow for start-up without carbon monoxide, which can representsignificant improvements in safety, process complexity and process cost.In certain embodiments, such processes also include raising the catalystbed temperature of each catalyst bed from no more than a firsttemperature to at least a second temperature. The catalyst bedtemperature(s) can be raised before or after the process gas isintroduced. In other embodiments, the process gas is introduced whilethe catalyst bed temperature(s) are raised. After the temperature israised, process gas can be flowed through the one or more catalyst bedsuntil a reactor effluent has less than 1 ppm acetylene (e.g., less than0.5 ppm acetylene).

The first temperature can, for example, represent a start-up temperatureof the reactor, for example, a temperature of the reactor system when itis not online. In certain embodiments, the first temperature is no morethan 50° C., e.g., in the range of 31-50° C., or 35-50° C., or 40-50°C., or 45-50° C. In certain embodiments, the first temperature is nomore than 45° C., e.g., in the range of 31-45° C., or 35-45° C., or40-45° C. In certain embodiments, the first temperature is no more than40° C., e.g., in the range of 31-40° C., or 35-40° C. But in otherembodiments, the first temperature is even cooler, for example, no morethan 30° C. or even, in some embodiments, no more than 25° C.

The second temperature can, for example, represent an operatingtemperature of the reactor, e.g., a temperature at which the reactoreffluent (for the particular process gas and other conditions beingused) has an acetylene concentration of no more than 1 ppm (e.g., nomore than 0.5 ppm). Thus, the second temperature can be a hydrogenationreaction temperature as described above. In certain embodiments, thesecond temperature is within the range of 40° C. to 140° C. In certaindesirable embodiments, the second temperature is within the range of 40°C. to 100° C., e.g., 40° C. to 90° C., or 50° C. to 90° C. But othersecond temperatures are possible. In some embodiments, the secondtemperature is within the range of 20° C. to 130° C., e.g., in the rangeof 20° C. to 120° C., or 20° C. to 110° C., or 20° C. to 100° C., or 20°C. to 90° C. In some embodiments, the second temperature is within therange of 40° C. to 140° C., e.g., 40° C. to 130° C., or 40° C. to 120°C., or 40° C. to 110° C. In some embodiments, the second temperature iswithin the range of 50° C. to 140° C., e.g., 50° C. to 130° C., or 50°C. to 120° C., or 50° C. to 110° C. In some embodiments, the secondtemperature is within the range of 60° C. to 140° C., e.g., 60° C. to130° C., or 60° C. to 120° C., or 60° C. to 110° C., or 60° C. to 100°C., or 60° C. to 90° C. The methods described herein can be used withconsiderable differences between the first temperature and the secondtemperature, e.g., at least 30° C., at least 40° C., at least 50° C. oreven at least 60° C.

The rise in temperature from no more than the first temperature to atleast the second temperature can advantageously be performed relativelyquickly. For example, in certain embodiments as otherwise describedherein, the temperature of each catalyst bed is raised from no more thanthe first temperature to at least the second temperature over a timeperiod of no more than 10 hours, e.g., no more than six hours, e.g., inthe range of 2-10 hours, 4-10 hours, or 3-6 hours. The rate oftemperature change can be, for example, in the range of 3-15° C./hour,e.g., in the range of 3-12° C./hour, or 6-15° C./hour, or 6-12° C./hour.

As described above, the process gas includes ethylene, acetylene andhydrogen. The process gas can have amounts of these materials and anyother components as otherwise described in any embodiment herein. Incertain embodiments, the process gas includes at least 10 ppm CO.

The first gas is non-reactive, as described above. In certainembodiments, the first gas includes no more than 1 ppm acetylene (e.g.,no more than 0.5 ppm). A variety of substances can be used as the firstgas, individually or in admixture. The first gas is non-reactive on thecatalyst bed at the first temperature and the second temperature.Accordingly, the first gas can in certain embodiments include lowamounts (or no) hydrogen and/or low amounts (or no) reducablehydrocarbon. In certain embodiments, the first gas includes less than 2%hydrogen, e.g., less than 1% hydrogen. Gases like nitrogen and fuel gascan be used.

In various methods described above, each catalyst bed is changed fromcontacting the first gas to contacting the process gas. The first gascan be present in the reactor at a relatively lower pressure than theprocess gas source, such that when process gas is admitted to thereactor without opening a reactor outlet, it can mix with the first gasto provide an overall reaction pressure. Desirably the difference inpressures is small enough that the process gas is significantly dilutedwhen it is first admitted to the reactor. For example, in one example ofan embodiment, the pressure of the first gas in the reactor can be200-300 psi, while the pressure of the process gas can be 400-500 psi.Once the first gas and the process gas mix in the reactor, flow can beestablished by allowing gas to escape the reactor. Of course, the personof ordinary skill in the art will appreciate that the particular methodof admitting the process gas to the reactor will depend on reactor andprocess design.

In certain desirable embodiments as otherwise described herein, theprocess gas itself can be used to pressure up the reactor to the reactorpressure at which the selective hydrogenation process is run. That is,in certain embodiments, there is no need to pre-pressurize with an inertgas up to the process pressure. Rather, the process gas can be used tobring the reactor up to process pressure. Advantageously, the highselectivity of the catalysts described herein allows the process gas toprovide initial reactor pressure with a much reduced risk of thermalrunaway.

The present inventors have determined that the catalysts describedherein can be brought to process temperature more quickly than previouscatalysts as a result of the high selectivity for acetylenehydrogenation. Accordingly, another aspect of the disclosure is a methodof starting up a selective hydrogenation reactor, the reactor housingone or more catalyst beds each containing a catalyst suitable forselectively hydrogenating acetylene in a process gas comprising at least10 mol. % ethylene, at least 1 ppm acetylene, and at least 5 mol. %hydrogen, the method comprising providing each catalyst bed at no morethan a first temperature, the catalyst of the catalyst bed being incontact with the gas; in the presence of the process gas, heating eachcatalyst bed to at least a second temperature, the second temperaturebeing at least 20 degrees greater than the first temperature, theheating of each catalyst bed being performed at a rate in the range ofat least 3° C./hour; and allowing the process gas to flow through thecatalyst bed until a concentration of acetylene at an outlet of thereactor is less than 1 ppm. In certain embodiments, the rate is in therange of 3-20° C./hour, e.g., 3-15° C./hour or 3-12° C./hour. In certainembodiments, the rate is in the range of 6-20° C./hour, e.g., 6-15°C./hour or 6-12° C./hour. In certain embodiments, the rate is in therange of 9-20° C./hour, e.g., 9-15° C./hour.

The catalysts described above with respect to the hydrogenation methodscan be suitable for use in the startup methods described herein.

As is conventional, the methods described herein can further include,before introducing the process gas to the bed or contacting the catalystcomposition with the process gas, reducing the catalyst (e.g., with aflow of a hydrogen-containing gas).

Another aspect of the disclosure is a hydrogenation catalyst compositionincluding a porous support, present in the composition in an amountwithin the range of 90 wt. % to 99.9 wt. %; palladium, present in thecomposition in an amount within the range of 0.02 wt. % to 0.5 wt. %(e.g., 0.04 wt. % to 0.15 wt. %), calculated on an elemental mass basis;and one or more ionic liquids, present in the composition in a combinedamount up to 10 wt. %. In certain embodiments, the catalyst compositionfurther includes at least one promoter (e.g., silver), present in thecomposition in an amount within the range of 0.05 wt. % to 0.25 wt. %,e.g., 0.08 wt. % to 0.25 wt. %, or 0.1 wt. % to 0.25 wt. %, calculatedon an elemental mass basis.

The amount of palladium in the catalyst composition can be, for example,within the range of 0.05 wt. % to 0.2 wt. %, or 0.05 wt. % to 0.15 wt.%, 0.07 wt. % to 0.2 wt. %, or 0.07 wt. % to 0.15 wt. %, or 0.08 wt. %to 0.2 wt. %, or 0.08 wt. % to 0.15 wt. %, or 0.1 wt. % to 0.2 wt. %, or0.1 wt. % to 0.15 wt. %, or 0.11 wt. % to 0.2 wt. %, or 0.11 wt. % to0.15 wt. %. The present inventors have determined that catalyst withrelatively large amounts of palladium can usefully provide highconversion and high selectivity without runaway.

Another aspect of the disclosure is a hydrogenation catalyst compositionincluding a porous support, present in the composition in an amountwithin the range of 90 wt. % to 99.9 wt. %; palladium, present in thecomposition in an amount of at least 0.02 wt. % (e.g., 0.04 wt. % to0.15 wt. %), calculated on an elemental mass basis; and one or moreionic liquids, present in the composition in a combined amount up to 10wt. %. In certain embodiments, the catalyst composition further includesat least one promoter (e.g., silver), present in the composition in anamount within the range of 0.05 wt. % to 0.25 wt. %, e.g., 0.08 wt. % to0.25 wt. %, or 0.1 wt. % to 0.25 wt. %, calculated on an elemental massbasis. In this aspect, the support has a BET surface area of no morethan 10 m²/g, and a pore volume of at least 0.1 mL/g. The BET surfacearea and pore volume of the support can otherwise be as described above.

Another aspect of the disclosure is a hydrogenation catalyst compositionincluding: a porous support, present in the composition in an amountwithin the range of 90 wt. % to 99.9 wt. %; palladium, present in thecomposition in an amount within the range of at least 0.02 wt. %,calculated on an elemental mass basis; and one or more ionic liquids,present in the composition in a combined amount up to 10 wt. %, whereinthe hydrogenation catalyst has a BET surface area of no more than 10m²/g and a pore volume of at least 0.05 mL/g. The present inventors havedetermined that impregnating with relatively little ionic liquid canprovide substantial pore volume remaining in the catalyst, i.e., suchthat pores accessible by mercury porosimetry are not completely filled.

In certain such embodiments, the hydrogenation catalyst compositioncomprises palladium in an amount of at least 0.03 wt. %, or at least0.04 wt. %, or at least 0.05 wt. %, or at least 0.06 wt. %, or at least0.07 wt. %, or at least 0.08 wt. %, or at least 0.09 wt. %, or at least0.1 wt. %, or at least 0.11 wt. %, or at least 0.12 wt. %, or at least0.13 wt. %, or at least 0.14 wt. %, or at least 0.15 wt. %. In certainsuch embodiments, the hydrogenation catalyst composition comprisespalladium in an amount of no more than 0.5 wt. % (e.g., no more than 0.4wt. %, or no more than 0.3 wt. %, or no more than 0.2 wt. %). Forexample, various embodiments include palladium in an amount within therange of 0.02 wt. % to 0.5 wt. %, or 0.02 wt. % to 0.45 wt. %, or 0.03wt. % to 0.4 wt. %, or 0.03 wt. % to 0.35 wt. %, or 0.04 wt. % to 0.3wt. %, or 0.04 wt. % to 0.25 wt. %.

Such hydrogenation catalysts can advantageously include a promoter asotherwise described herein.

In certain desirable embodiments, such hydrogenation catalysts have aBET surface area within the range of 2 m²/g to 10 m²/g, e.g., within therange of 2 m²/g to 9 m²/g, or 2 m²/g to 8 m²/g, or 2 m²/g to 7 m²/g, or2 m²/g to 6 m²/g, or 2 m²/g to 5 m²/g, or 3 m²/g to 10 m²/g, or 4 m²/gto 10 m²/g, or 5 m²/g to 10 m²/g, or 6 m²/g to 10 m²/g, or 2 m²/g to 6m²/g, or 3 m²/g to 7 m²/g, or 4 m²/g to 8 m²/g, or 5 m²/g to 9 m²/g.

In certain desirable embodiments, such hydrogenation catalysts have apore volume in the range of 0.05 mL/g to 1.0 mL/g, e.g., 0.05 mL/g to0.4 mL/g. In certain such embodiments, the hydrogenation catalyst has apore volume in the range of 0.10 mL/g to 1.0 mL/g, e.g., 0.10 mL/g to0.80 mL/g, or 0.10 to 0.60 mL/g, or 0.10 to 0.40 mL/g, or 0.10 to 0.30mL/g, or in the range of 0.20 mL/g to 1.0 mL/g, e.g., 0.20 mL/g to 0.80mL/g, or 0.20 to 0.60 mL/g, or 0.20 to 0.40 mL/g, or 0.20 to 0.35 mL/g,or in the range of 0.40 mL/g to 1.0 mL/g, e.g., 0.40 mL/g to 0.80 mL/g,or 0.40 to 0.60 mL/g.

Desirably, catalysts of the disclosure include an ionic liquid in anamount that does not completely fill the pore volume of the support. Forexample, in certain embodiments as otherwise described herein, thedifference between the pore volume of the support and the pore volume ofthe catalyst (i.e., including the palladium, any promoters and the ionicliquid) is in the range of 10-90% of the pore volume of the support. Incertain such embodiments, the difference is in the range of 20-90% ofthe pore volume of the support, e.g., 30-90% or 40-90%. In certain suchembodiments, the difference is in the range of 10-80% of the pore volumeof the support, e.g., 20-80%, or 30-80%, or 40-80%. In certain suchembodiments, the difference is in the range of 10-70% of the pore volumeof the support, e.g., 20-70%, or 30-70%, or 40-70%. In certain suchembodiments, the difference is in the range of 10-60% of the pore volumeof the support, e.g., 20-60%, or 30-60%, or 40-60%.

The catalysts of the disclosure can include a variety of amounts ofionic liquid. For example, in certain embodiments as otherwise describedherein, the ionic liquid is present in an amount in the range of 0.1 wt.% to 10 wt. %, e.g., 0.1 wt. % to 8 wt. %, or 0.1 wt. % to 6 wt. %, or0.1 wt. % to 4 wt. %, or 0.1 wt. % to 3 wt. %, or 0.1 wt. % to 2 wt. %,or 0.1 wt. % to 1 wt. %, e.g., 0.2 to 3 wt. %, or 0.5-4 wt. %.

The catalysts according to these aspects of the disclosure can otherwisebe as described above with respect to catalysts useful in the methods ofthe disclosure. Moreover, the catalysts according to this aspect of thedisclosure can be used in any of the methods as otherwise describedherein.

The processes and materials described herein can be especially useful infront-end applications. However, the person of ordinary skill in the artwill appreciate that they can be used in a variety of otherapplications, especially those in which risk of runaway (e.g., due tohigh hydrogen concentrations) is problematic.

EXAMPLES

The Examples that follow are illustrative of specific embodiments of theinvention, and various uses thereof. They are set forth for explanatorypurposes only, and are not to be taken as limiting the invention.

Example 1. Selective Hydrogenation Catalyst Preparation

An alpha-alumina porous support (4-mm tablets) having a BET surface areaof 5±2 m²/g was impregnated by aqueous solutions of silver salt andpalladium salt and calcined at minimum 260° C. in air for 2 hours. Thesilver content in silver salt aqueous solution and palladium content isthe palladium salt solution were adjusted to make a final calcinedimpregnated support having 0.050±0.005 wt. % palladium and 0.070±0.005wt. % silver. The palladium was localized within the outer 500 μm of theporous support. The pore volume of the metal-impregnated support was0.26 mL/g.

The calcined impregnated support was further impregnated with an aqueoussolution of about 0.5 wt. % of an ionic liquid (IL) on the dryimpregnated support. The resulting material was dried at up to 150° C.for 2 hours to provide catalyst A1. The catalyst had a pore volume of0.23 mL/g.

Catalyst A2 was prepared in a manner similarly to that of catalyst A1. Acomparative catalyst C was also provided, which does not contain IL andhas a Pd loading even less than that of catalysts A1 and A2.

TABLE 1 Catalyst Compositions No. Pd (wt. %) Ag (wt. %) IL (wt. %) A10.05 0.07 0.5 A2 0.08 0.11 0.5 C 0.02 0.05 0.0

Example 2. Selective Hydrogenation

Catalysts prepared according to Example 1 were placed in a 15 mLcatalyst bed in a reactor tube. The catalyst was reduced in a hydrogenflow with gas hourly space velocity of >500 h⁻¹ at 94° C. for one hourprior to introducing feed gas mixture into the reactor. A gas mixturecontaining 200 ppm CO, 19 mol. % H₂, 0.35 mol. % C₂H₂, 30 mol. % C₂H₄,45 mol. % CH₄ and balance nitrogen was passed over the catalyst bed at aGHSV of 7,000 h⁻¹, at a total pressure of 500 psig. The catalyst bed washeated using a water bath, in intervals of 2-5° C., starting from 40° C.The concentration of acetylene and ethane were monitored at the reactoroutlet, and are shown in FIG. 1 . As shown in FIG. 1 , the temperatureat which the concentration of acetylene at the reactor outlet decreasesto 25 ppm (i.e., an indicator of activity; T₁) is similar for catalystA1 and C, but the operating window of catalyst A1 (i.e., the differencebetween the runaway temperature, T₂ (the temperature at which theconcentration of ethane at the reactor outlet reaches 2 mol. %) and T₁is significantly larger than that of catalyst C—71° C. vs. 21° C.,respectively.

Example 3. CO Swing Test

Catalysts prepared according to Example 1 were placed in a 15 mLcatalyst bed in a reactor tube. The catalyst was reduced in a hydrogenflow with gas hourly space velocity of >500 h⁻¹ at 94° C. for one hourprior to introducing feed gas mixture into the reactor. A gas mixturecontaining 200 ppm CO, 0.5 mol. % C₂H₂, 19 mol. % H₂, 26 mol. % C₂H₄, 40mol. % CH₄ and balance nitrogen was passed over the catalyst bed at aGHSV of 7,000 h⁻¹. The catalyst bed was heated to a temperaturesufficient to provide an acetylene concentration of 20-30 ppm at thereactor outlet. The ethylene selectivity of the process was continuouslymonitored at the reactor outlet, and is shown in FIG. 2 .

At 25 and 45 hours on stream, the CO concentration of the gas mixturewas briefly lowered to 60 ppm, without lowering the temperature of thereactor bed. At 285 hours on stream, the CO concentration of the gasmixture was increased to 340 ppm, and the temperature of the reactor bedwas adjusted to provide 95% acetylene conversion. The CO concentrationwas subsequently lowered to 60 ppm, and then raised to 200 ppm. At 308hours on stream, the cycle performed at 285 hours on stream wasrepeated. The results, shown in FIG. 2 , demonstrate that the recoveryof the ethylene selectivity of catalyst A1 after variations in theconcentration of CO is significantly better than that of catalyst C.Moreover, the results demonstrate that the selectivity of catalyst A1remains higher than that of catalyst C in both high and lowconcentrations of CO.

Example 4. Selective Hydrogenation

Catalysts prepared according to Example 1 were placed in a 15 mLcatalyst bed in a reactor tube. The catalyst was reduced in a hydrogenflow with gas hourly space velocity of >500 h⁻¹ at 94° C. for one hourprior to introducing feed gas mixture into the reactor. A gas mixturecontaining 350 ppm CO, 17 mol. % H₂, 0.69 mol. % C₂H₂, 47 mol. % C₂H₄,11 mol. % CH₄, 4 mol. % propylene, 0.098 ppm propadiene, 0.13 ppm methylacetylene, and 130 ppm 1,3-butadiene was passed over the catalyst bed ata GHSV of either 4,500 h⁻¹ or 13,000 h⁻¹, at a total pressure of 500psig. The catalyst bed was heated using a water bath, in intervals of 5°C. The acetylene conversion and ethylene selectivity were continuouslymonitored at the reactor outlet, and are shown in FIG. 3 . Notably, theassociated increase in temperature necessary to maintain a desiredacetylene conversion at 13,000 h⁻¹ GHSV relative to 4,500 h⁻¹ is 10-12°C. for catalyst C, but only 8-10° C. for catalyst A1. Moreover, at13,000 h⁻¹, the ethylene selectivity of catalyst A1 remained above 95%when acetylene conversion was as high as 95%, and the ethyleneselectivity of catalyst A1 remained above 50% when the acetyleneconversion was maintained above 99%.

Example 5. Selective Hydrogenation

Catalysts prepared according to Example 1 were placed in a 15 mLcatalyst bed in a reactor tube. The catalyst was reduced in a hydrogenflow with gas hourly space velocity of >500 h⁻¹ at 94° C. for one hourprior to introducing feed gas mixture into the reactor. A gas mixturecontaining 200 ppm CO, 19 mol. % H₂, 0.35 mol. % C₂H₂, 30 mol. % C₂H₄,45 mol. % CH₄ and balance nitrogen was passed over the catalyst bed at aGHSV of either 7,000 h⁻¹ or 28,000 h⁻¹, at a total pressure of 500 psig.The catalyst bed was heated using a water bath, in intervals of 2-5° C.,starting from 40° C. The acetylene conversion and ethylene selectivitywere continuously monitored at the reactor outlet, and are shown in FIG.4 . Notably, the ethylene selectivity of catalyst A2 at 28,000 h⁻¹ wassimilar to that of catalyst C at only 7,000 h⁻¹, i.e., the processcapacity was about 4 times higher for catalyst A2.

Example 6. Reactor Startup without CO Pre-Treatment

Commercial Front End selective hydrogenation plants typically requirepre-treatment of the catalyst bed with CO at start-up to prevent thereactor temperature from runaway when process gas is first introduced tothe reactor due to non-selective hydrogenation of ethylene to ethane.

A series of start-up tests were performed in a laboratory-scale testunit using catalyst A1 without CO pre-treatment and compared to the basecase with CO gas pre-treatment of the catalyst. Tests were run at GHSVvalues of 7000 h⁻¹.

The comparative start-up process in the laboratory-scale test included aH₂ reduction at 94° C. for 1 hour followed by a CO pre-treatment purgeprior to bringing all feed gases on stream. In this comparative test, 1%CO in CH₄ gas was used to purge the system for 20 minutes at 30° C. andto pressurize the reactor to 35 bar, then the feed gas containing 0.02%CO, 20% H₂, 3500 ppm C₂H₂, and 27% C₂H₄ was bought on stream at 35 bar.The water bath temperature remained at 30° C., while catalyst bed topand bottom temperatures were monitored during the test. Data are shownin FIG. 5 . The first temperature point was when the pressure-up beganwith just the CO/CH₄ gas. The pressure-up with CO/CH₄ took over 1-2minutes. Initially, there was a brief 2-3° C. exotherm for ˜5 min. Theintroduction of feed gas at 30° C. and 35 bar did not cause asignificant exotherm. Reactor outlet gas sample was analysed at 15minutes after catalyst bed temperatures were stable. The outlet ethaneconcentration was stable at 120 ppm, which was from inlet feed.

Next, the start-up test was repeated in substantially the same manner,but replacing the CO/CH₄ pretreatment with an N₂ pre-treatment, followedby introducing feed gas at atmosphere pressure and pressurizing thereactor using feed gas at the flow rate of 7000 h−1 GHSV. The water bathtemperature remained at 30° C., top and bottom temperatures weremonitored during the test. It took ˜10 min reach the 35 bar targetpressure. Data are shown in FIG. 6 .

During the 10 min the of pressure-up period, a 2 to 3° C. exotherm wasobserved, and both top and bottom temperatures returned to below 30° C.after gas flow was stabilized at 35 bar, when a gas sample of reactoroutlet was analysed showing in excess of 2% ethane. This initial ethaneformation was due to the fact that there was no flow from reactor duringpressure-up before the reactor reaching 35 bar. Continuous analysis ofoutlet sample after inlet and outlet flow were stabilized at 35 barshowed that the ethane content at reactor outlet dropped to about 120ppm, indicating no sustained formation of ethane in the reactor.

Another start-up test was performed, this time, omitting the N₂ purgebetween the hydrogen reduction and introduction of the feed gas.Instead, the catalyst was purged with feed gas containing 0.02% CO, 20%H₂, 3500 ppm C₂H₂, and 27% C₂H₄ CO, for 20 minutes before beingpressured up to 35 bar with the feed gas. This was done to simulaterecirculation of gases prior to start-up in plant conditions.Temperature measurements started at the beginning of the pressure-up;data is shown in FIG. 7 . No temperature change was noticed during the20 min feed purge. Both top and bottom temperatures started to increaseduring the pressure-up and top temperature exceed the bottom temperatureslightly. Ethane formation during this temperature spike was around 10%.Temperatures eventually returned to normal after 10 min. Ethaneformation continued to decline throughout the test until becoming stableat 120 ppm.

Finally, the start-up procedure using feed gas to purge as describedabove was applied to catalyst C. FIG. 8 shows that catalyst bedtemperature change and ethane formation during the start-up test. Thetemperature measurements started at once feed is introduced. The toptemperature started to increase before pressure-up, exceeding the bottomtemperature at the beginning of pressure-up. The top temperature droppedslightly after pressure-up and continuous gas flow was established, butthen continued to increases until stabilizing at 36° C. The toptemperature did not return to below 30°. The ethane formation duringthis time was stable at ˜16%, indicating sustained thermal runaway.

Thus, the start-up experiments described above demonstrate thatcatalysts including ionic liquids can provide a low risk of thermalrunaway, even in the absence of CO pre-treatment.

Example 7. Insensitivity to Carbon Monoxide Concentration

A study of sensitivity to carbon monoxide concentration was performedunder isothermal conditions. Notably, the selectivity of Catalyst A1 wasrelatively insensitive to carbon monoxide concentration, while thesensitivity of Catalyst C was much more sensitive to carbon monoxideconcentrations. In adiabatic systems, an increased exotherm fromincreased ethylene hydrogenation at lower CO concentrations even furtherdecreases the selectivity, potentially triggering exothermic runaway.Notably, these data demonstrate that the catalysts described herein canbe used under a wide variety of conditions even at low COconcentrations.

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the preferred embodiments of the presentinvention only and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual aspects of various embodiments of theinvention. In this regard, no attempt is made to show structural detailsof the invention in more detail than is necessary for the fundamentalunderstanding of the invention, the description taken with the drawingsand/or examples making apparent to those skilled in the art how theseveral forms of the invention may be embodied in practice. Thus, beforethe disclosed processes and devices are described, it is to beunderstood that the aspects described herein are not limited to specificembodiments, apparatuses, or configurations, and as such can, of course,vary. It is also to be understood that the terminology used herein isfor the purpose of describing particular aspects only and, unlessspecifically defined herein, is not intended to be limiting.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the invention (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.Recitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. Ranges can be expressed herein as from“about” one particular value, and/or to “about” another particularvalue. When such a range is expressed, another aspect includes from theone particular value and/or to the other particular value. Similarly,when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms anotheraspect. It will be further understood that the endpoints of each of theranges are significant both in relation to the other endpoint, andindependently of the other endpoint.

All methods described herein can be performed in any suitable order ofsteps unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein is intended merely to betterilluminate the invention and does not pose a limitation on the scope ofthe invention otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element essential to thepractice of the invention.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words ‘comprise’, ‘comprising’, and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to”. Words using the singular or pluralnumber also include the plural and singular number, respectively.Additionally, the words “herein,” “above,” and “below” and words ofsimilar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portions of theapplication.

As will be understood by one of ordinary skill in the art, eachembodiment disclosed herein can comprise, consist essentially of orconsist of its particular stated element, step, ingredient or component.As used herein, the transition term “comprise” or “comprises” meansincludes, but is not limited to, and allows for the inclusion ofunspecified elements, steps, ingredients, or components, even in majoramounts. The transitional phrase “consisting of” excludes any element,step, ingredient or component not specified. The transition phrase“consisting essentially of” limits the scope of the embodiment to thespecified elements, steps, ingredients or components and to those thatdo not materially affect the embodiment.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. When further clarity is required, the term “about” has themeaning reasonably ascribed to it by a person skilled in the art whenused in conjunction with a stated numerical value or range, i.e.,denoting somewhat more or somewhat less than the stated value or rangewithin normal ranges of uncertainty and imprecision in the art.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember may be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group may be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Some embodiments of this invention are described herein, including thebest mode known to the inventors for carrying out the invention. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than specifically described herein. Accordingly,this invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

Furthermore, numerous references have been made to patents and printedpublications throughout this specification. Each of the cited referencesand printed publications are individually incorporated herein byreference in their entirety.

In closing, it is to be understood that the embodiments of the inventiondisclosed herein are illustrative of the principles of the presentinvention. Other modifications that may be employed are within the scopeof the invention. Thus, by way of example, but not of limitation,alternative configurations of the present invention may be utilized inaccordance with the teachings herein. Accordingly, the present inventionis not limited to that precisely as shown and described.

Additional embodiments of the disclosure are provided by the enumeratedembodiments below, which can be combined in any number and in anyfashion that is logically and technically consistent.

Embodiment 1

A method for selectively hydrogenating acetylene, the method comprisingcontacting a catalyst composition comprising a porous support,palladium, and at least one ionic liquid with a process gas comprising

-   -   ethylene, present in the process gas in an amount of at least 10        mol. %;    -   acetylene, present in the process gas in an amount of at least 1        ppm;    -   hydrogen, present in the process gas in amount of at least 5        mol. %; and 0 ppm to 190 ppm carbon monoxide;

-   wherein at least 90% of the acetylene present in the process gas is    hydrogenated, and no more than 1 mol. % of the total of acetylene    and ethylene present in the process gas is converted to ethane.

Embodiment 2

A method for selectively hydrogenating acetylene, the method comprisingcontacting a catalyst composition comprising a porous support,palladium, and at least one ionic liquid with a process gas comprising

-   -   ethylene, present in the process gas in an amount of at least 10        mol. %;    -   acetylene, present in the process gas in an amount of at least 1        ppm;    -   hydrogen, present in the process gas in amount of at least 5        mol. %; and at least 600 ppm carbon monoxide;

-   wherein at least 90% of the acetylene present in the process gas is    hydrogenated, and no more than 1 mol. % of the total of acetylene    and ethylene present in the process gas is converted to ethane.

Embodiment 3

A method according to Embodiment 1 or 2, wherein the process gas iscontacted with the catalyst at a gas hourly space velocity (GHSV) withinthe range of 2,000 h⁻¹ to 40,000 h⁻¹.

Embodiment 4

A method for selectively hydrogenating acetylene, the method comprisingcontacting a catalyst composition comprising a porous support,palladium, and one or more ionic liquids with a process gas comprising

-   -   ethylene, present in the process gas in an amount of at least 10        mol. %;    -   acetylene, present in the process gas in an amount of at least 1        ppm; and    -   hydrogen, present in the process gas in an amount of at least 5        mol. %;

-   wherein the process gas is contacted with the catalyst at a gas    hourly space velocity (GHSV) based on total catalyst bed volume    (i.e., in one bed or multiple beds) of at least 7,100 h⁻¹ (e.g.,    7,500 h⁻¹ to 40,000 h⁻¹); and

-   wherein at least 90% of the acetylene present in the process gas is    hydrogenated, and no more than 1 mol. % of the total of acetylene    and ethylene present in the process gas is converted to ethane.

Embodiment 5

A method according to claim 4, wherein carbon monoxide is present in theprocess gas in an amount up to 20,000 ppm, e.g., up to 10,000 ppm, or upto 5,000 ppm, or up to 2,500 ppm, or up to 1,200 ppm, or up to 1,000ppm.

Embodiment 6

A method according to claim 4, wherein carbon monoxide is present in theprocess gas in an amount up to 100 ppm, or up to 500 ppm, or up to 1,000ppm, or up to 5,000 ppm, or in the range of 10 ppm to 5,000 ppm, or inthe range of 10 ppm to 1,200 ppm, or in the range of 10 ppm to 500 ppm,or in the range of 50 ppm to 5,000 ppm, or in the range of 50 ppm to1,200 ppm, or in the range of 50 ppm to 500 ppm, or in the range of 75ppm to 1,200 ppm, or in the range of 75 ppm to 500 ppm.

Embodiment 7

A method according to any of embodiments 1, 3 and 4, wherein carbonmonoxide is present in the process gas in an amount up to 190 ppm, e.g.,up to 175 ppm, or within the range of 1 ppm to 190 ppm, or in the rangeof 5 ppm to 190 ppm, or 10 ppm to 190 ppm, or 25 ppm to 190 ppm, or 50ppm to 190 ppm, or 75 ppm to 190 ppm, or 1 ppm to 175 ppm, or 5 ppm to175 ppm, or 10 ppm to 175 ppm, or 25 ppm to 175 ppm, or 50 ppm to 175ppm, or 100 ppm to 175 ppm.

Embodiment 8

A method according to any of embodiments 1, 3 and 4, wherein carbonmonoxide is present in the process gas in an amount up to 150 ppm, forexample, up to 140 ppm, e.g., within the range of 1 ppm to 150 ppm, or 5ppm to 150 ppm, or 10 ppm to 150 ppm, or 25 ppm to 150 ppm, or 50 ppm to150 ppm, or 75 ppm to 150 ppm, or 1 ppm to 140 ppm, or 5 ppm to 140 ppm,or 10 ppm to 140 ppm, or 25 ppm to 140 ppm, or 50 ppm to 140 ppm, or 75ppm to 140 ppm.

Embodiment 9

A method according to any of embodiments 1, 3 and 4, wherein carbonmonoxide is present in the process gas in an amount up to 125 ppm, forexample, up to 115 ppm, e.g., within the range of 1 ppm to 125 ppm, or 5ppm to 125 ppm, or 10 ppm to 125 ppm, or 25 ppm to 125 ppm, or 50 ppm to125 ppm, or 75 ppm to 125 ppm, or 1 ppm to 115 ppm, or 5 ppm to 115 ppm,or 10 ppm to 115 ppm, or 25 ppm to 115 ppm, or 50 ppm to 115 ppm, or 75ppm to 115 ppm.

Embodiment 10

A method according to any of embodiments 1, 3 and 4, wherein carbonmonoxide is present in the process gas in an amount up to 110 ppm, forexample, up to 100 ppm, e.g., within the range of 1 ppm to 110 ppm, or 5ppm to 110 ppm, or 10 ppm to 110 ppm, or 25 ppm to 110 ppm, or 50 ppm to110 ppm, or 75 ppm to 110 ppm, or 1 ppm to 100 ppm, or 5 ppm to 100 ppm,or 10 ppm to 100 ppm, or 25 ppm to 100 ppm, or 50 ppm to 100 ppm.

Embodiment 11

A method according to any of embodiments 1, 3 and 4, wherein carbonmonoxide is present in the process gas in an amount up to 95 ppm, forexample, up to 90 ppm, e.g., within the range of 1 ppm to 95 ppm, or 5ppm to 95 ppm, or 10 ppm to 95 ppm, or 25 ppm to 95 ppm, or 50 ppm to 95ppm, or 1 ppm to 90 ppm, or 5 ppm to 90 ppm, or 10 ppm to 90 ppm, or 25ppm to 90 ppm, or 50 ppm to 90 ppm.

Embodiment 12

A method according to any of embodiments 1, 3 and 4, wherein carbonmonoxide is present in the process gas in an amount up to 85 ppm, forexample, up to 80 ppm, e.g., within the range of 1 ppm to 85 ppm, or 5ppm to 85 ppm, or 10 ppm to 85 ppm, or 25 ppm to 85 ppm, or 50 ppm to 85ppm, or 1 ppm to 80 ppm, or 5 ppm to 80 ppm, or 10 ppm to 80 ppm, or 25ppm to 80 ppm, or 50 ppm to 80 ppm.

Embodiment 13

A method according to any of embodiments 1-12, wherein carbon monoxideis not added to a feed gas stream to provide the process gas.

Embodiment 14

A method according to any of embodiments 2-4, wherein carbon monoxide ispresent in the process gas in an amount within the range of 600 ppm to20,000 ppm, or 600 ppm to 15,000 ppm, or 600 ppm to 12,500 ppm, or 700ppm to 10,000 ppm, or 800 ppm to 7,500 ppm, or 900 ppm to 5,000 ppm, or700 ppm to 5,000 ppm, or 800 ppm to 5,000 ppm.

Embodiment 15

A method according to any of embodiments 2-4, wherein carbon monoxide ispresent in the process gas in an amount within the range of 800 ppm to20,000 ppm, or 800 ppm to 15,000 ppm, or 800 ppm to 10,000 ppm, or 800ppm to 5,000 ppm, or 800 ppm to 2,500 ppm, or 800 ppm to 1,500 ppm.

Embodiment 16

A method according to any of embodiments 2-4, wherein carbon monoxide ispresent in the process gas in an amount within the range of 1,000 ppm to20,000 ppm, or 1,000 ppm to 15,000 ppm, or 1,000 ppm to 10,000 ppm, or1,000 ppm to 5,000 ppm, or 1,000 ppm to 2,500 ppm.

Embodiment 17

A method according to any of embodiments 2-4, wherein carbon monoxide ispresent in the process gas in an amount within the range of 1,500 ppm to20,000 ppm, or 1,500 ppm to 15,000 ppm, or 1,500 ppm to 10,000 ppm, or1,500 ppm to 5,000 ppm.

Embodiment 18

A method according to any of embodiments 2-4, wherein carbon monoxide ispresent in the process gas in an amount within the range of 2,000 ppm to20,000 ppm, or 2,000 ppm to 15,000 ppm, or 2,000 ppm to 10,000 ppm, or2,000 ppm to 5,000 ppm.

Embodiment 19

A method according to any of embodiments 1, 2 and 4-18, wherein theprocess gas is contacted with the catalyst at a GHSV of at least 7,100h⁻¹, e.g., within the range of 7,100 h⁻¹ to 40,000 h⁻¹, or 7,100 h⁻¹ to30,000 h⁻¹, or 7,100 h⁻¹ to 20,000 h⁻¹.

Embodiment 20

A method according to any of embodiments 1, 2 and 4-18, wherein theprocess gas is contacted with the catalyst at a GHSV of at least 7,500h⁻¹, e.g., within the range of 7,500 h⁻¹ to 40,000 h⁻¹, or 7,500 h⁻¹ to30,000 h⁻¹, or 7,500 h⁻¹ to 20,000 h⁻¹.

Embodiment 21

A method according to any of embodiments 1, 2 and 4-18, wherein theprocess gas is contacted with the catalyst at a GHSV of at least 10,000h⁻¹, e.g., within the range of 10,000 h⁻¹ to 40,000 h⁻¹, or 10,000 h⁻¹to 30,000 h⁻¹, or 10,000 h⁻¹ to 20,000 h⁻¹.

Embodiment 22

A method according to any of embodiments 1, 2 and 4-18, wherein theprocess gas is contacted with the catalyst at a GHSV of at least 12,500h⁻¹, e.g., within the range of 12,500 h⁻¹ to 40,000 h⁻¹, or 12,500 h⁻¹to 30,000 h⁻¹, or 12,500 h⁻¹ to 20,000 h⁻¹.

Embodiment 23

A method according to any of embodiments 1, 2 and 4-18, wherein theprocess gas is contacted with the catalyst at a GHSV of at least 15,000h⁻¹, e.g., within the range of 15,000 h⁻¹ to 40,000 h⁻¹, or 15,000 h⁻¹to 30,000 h⁻¹, or 15,000 h⁻¹ to 20,000 h⁻¹.

Embodiment 24

A method according to any of embodiments 1, 2 and 4-18, wherein theprocess gas is contacted with the catalyst at a GHSV of at least 20,000h⁻¹, e.g., within the range of 20,000 h⁻¹ to 40,000 h⁻¹, or 20,000 h⁻¹to 30,000 h⁻¹.

Embodiment 25

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 20° C.to 140° C.

Embodiment 26

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 40° C.to 100° C.

Embodiment 27

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 40° C.to 90° C.

Embodiment 28

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 50° C.to 90° C.

Embodiment 29

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 50° C.to 100° C.

Embodiment 30

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 20° C.to 130° C., e.g., in the range of 20° C. to 120° C., or 20° C. to 110°C., or 20° C. to 100° C., or 20° C. to 90° C.

Embodiment 31

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 40° C.to 140° C., e.g., 40° C. to 130° C., or 40° C. to 120° C., or 40° C. to110° C.

Embodiment 32

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 50° C.to 140° C., e.g., 50° C. to 130° C., or 50° C. to 120° C., or 50° C. to110° C.

Embodiment 33

A method according to any of embodiments 1-24, wherein the selectivehydrogenation is conducted at a temperature within the range of 60° C.to 140° C., e.g., 60° C. to 130° C., or 60° C. to 120° C., or 60° C. to110° C., or 60° C. to 100° C., or 60° C. to 90° C.

Embodiment 34

A method according to any of embodiments 1-33, wherein at least 95% ofthe acetylene present in the process gas is hydrogenated, e.g., at least96%, or at least 97%, or at least 97.5% of the acetylene present in theprocess gas is hydrogenated.

Embodiment 35

A method according to any of embodiments 1-33, wherein at least 98% ofthe acetylene present in the process gas is hydrogenated, e.g., at least98.5%, or at least 99% of the acetylene present in the process gas ishydrogenated.

Embodiment 36

A method according to any of embodiments 1-33, wherein essentially allof the acetylene present in the process gas is hydrogenated.

Embodiment 37

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than 1mol. % greater than the amount of ethane in the process gas.

Embodiment 38

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than 0.9mol. %, e.g., no more than 0.8 mol. % greater than the amount of ethanein the process gas.

Embodiment 39

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than 0.7mol. %, e.g., no more than 0.6 mol. % greater than the amount of ethanein the process gas.

Embodiment 40

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than 0.5mol. % greater than the amount of ethane in the process gas.

Embodiment 41

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than 0.2mol. % greater than the amount of ethane in the process gas.

Embodiment 42

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than 0.1mol. % greater than the amount of ethane in the process gas.

Embodiment 43

A method according to any of embodiments 1-36, wherein the amount ofethane in the product of the selective hydrogenation is no more than0.05 mol. % greater than the amount of ethane in the process gas.

Embodiment 44

A method according to any of embodiments 1-44, wherein ethylene ispresent in the process gas in an amount in the range of 10 mol. % to 70mol. %, or 15 mol. % to 60 mol. %, or 15 mol. % to 50 mol. %.

Embodiment 45

A method according to any of embodiments 1-44, wherein ethylene ispresent in the process gas in an amount of at least 20 mol. %, e.g., inthe range of 20 mol. % to 70 mol. %, or 20 mol. % to 60 mol. %, or 20mol. % to 50 mol. %.

Embodiment 46

A method according to any of embodiments 1-44, wherein ethylene ispresent in the process gas in an amount of at least 30 mol. %, e.g., inthe range of 30 mol. % to 70 mol. %, or 30 mol. % to 60 mol. %, or 30mol. % to 50 mol. %.

Embodiment 47

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount of at least 10 ppm, e.g., atleast 50 ppm.

Embodiment 48

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount of at least 100 ppm, e.g., atleast 500 ppm.

Embodiment 49

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount in the range of 10 ppm to 2 mol.%, e.g., 10 ppm to 1 mol. %, or 10 ppm to 0.5 mol %.

Embodiment 50

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount in the range of 50 ppm to 2 mol.%, e.g., 50 ppm to 1 mol. %, or 50 ppm to 0.5 mol %.

Embodiment 51

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount in the range of 100 ppm to 2mol. %, e.g., 100 ppm to 1 mol. %, or 100 ppm to 0.5 mol. %.

Embodiment 52

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount in the range of 500 ppm to 2mol. %, or 500 ppm to 1 mol. %, or 500 ppm to 0.5 mol. %.

Embodiment 53

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount of at least 0.1 mol. %, e.g., atleast 0.5 mol % or at least 1 mol. %.

Embodiment 54

A method according to any of embodiments 1-47, wherein acetylene ispresent in the process gas in an amount in the range of 0.1 mol. % to 2mol. %, e.g., 0.5 mol. % to 2 mol. %, or 1 mol. % to 2 mol. %, or 0.1mol. % to 1.5 mol. %, or 0.5 mol. % to 1.5 mol. %, or 1 mol. % to 1.5mol. %, or 0.1 mol. % to 1 mol. %, or 0.5 mol. % to 1 mol. %.

Embodiment 55

A method according to any of embodiments 1-54, wherein hydrogen ispresent in the process gas in an amount of least 6 mol. %, or at least 7mol. %, or at least 8 mol. %, or at least 9 mol. %, or at least 10 mol.%.

Embodiment 56

A method according to any of embodiments 1-54, wherein hydrogen ispresent in the process gas in an amount in the range of 5 mol. % to 50mol. %, e.g., 5 mol. % to 35 mol. %, or 5 mol. % to 20 mol. %, or 5 mol.% to 15 mol. %, or 8 mol. % to 50 mol. %, or 8 mol. % to 35 mol. %, or 8mol. % to 20 mol. %, or 8 mol. % to 15 mol. %, or 10 mol. % to 50 mol.%, or 10 mol. % to 35 mol. %, or 10 mol. % to 20 mol. %, or 10 mol. % to15 mol. %.

Embodiment 57

The method according to any of embodiments 1-56, wherein the process gasis provided from an effluent of a cracking process, from an overheadstream of a depropanizer, from an overhead stream of a de-ethanizer, orfrom a refiner off-gas stream.

Embodiment 58

The method according to any of embodiments 1-57, wherein the process gascontains no more than 10 mol. % (e.g., no more than 5 mol. %, or no morethan 2 mol. %, or no more than 1 mol. %) of carbon-containing componentsother than C₁ components (e.g., methane, carbon monoxide, and carbondioxide), C₂ components (e.g., ethylene, ethane, and acetylene) and C₃components (e.g., propane, propylene, propane, methyl acetylene, andpropadiene).

Embodiment 59

The method according to any of embodiments 1-57, wherein the process gascontains no more than 20 mol. % (e.g., no more than 15 mol. %, no morethan 10 mol. % or no more than 5 mol. %) of carbon-containing componentsother than ethylene, ethane, acetylene, carbon monoxide, carbon dioxideand methane.

Embodiment 60

A method according to any of embodiments 1-59, wherein the catalystcomposition comprises a porous support selected from alumina, silica,titania, and mixtures thereof, present in the catalyst composition in anamount within the range of 90 wt. % to 99.9 wt. %, e.g., 92.5 wt. % to99.9 wt. %, or 95 wt. % to 99.9 wt. %, or 97.5 wt. % to 99.9 wt. %.

Embodiment 61

A method according to embodiment 60, wherein the porous support is aporous alumina support, e.g., a porous alpha-alumina support.

Embodiment 62

A method according to any of embodiments 1-61, wherein the catalystcomposition comprises palladium in an amount of at least 0.02 wt. %,e.g., within the range of 0.02 wt. % to 0.5 wt. %, or 0.03 wt. % to 0.4wt. %, or 0.04 wt. % to 0.3 wt. %.

Embodiment 63

A method according to any of embodiments 1-62, wherein the catalystcomposition comprises the at least one ionic liquid in a total amount upto 10 wt. %.

Embodiment 64

A method according to any of embodiments 1-62, wherein the catalystcomposition comprises the at least one ionic liquid in an amount in therange of 0.5 wt. % to 4 wt. %, or 0.5 wt. % to 3 wt. %, or 0.5 wt. % to2 wt. %.

Embodiment 65

A method according to any of embodiments 1-64, wherein the shellthickness of the ionic liquid at an outer surface of the catalyst is inthe range of 10 to 2000 μm, e.g., 100 to 1000 μm, or 100 to 800 μm.

Embodiment 66

A method according to any of embodiments 1-65, wherein the at least oneionic liquid is selected from 1-butyl-3-methylimidazolium triflate,1-ethyl-3-methylpyridinium ethylsulfate, 1-butyl-1-methylpyrrolidiniumtriflate, 1-butyl-2,3-dimethylimidazolium triflate,1-butyl-3-methylimidazolium tricyanomethane, 1-butyl-3-methylimidazoliummethylsulfate, 1-butyl-3-methylimidazolium octylsulfate,1-butyl-3-methylimidazolium tetrafluoroborate,1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazoliummethylphosphonate, 1-ethyl-3-methylimidazolium triflate,1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide,1-butyl-1-methylpyrrolidinium tetracyanoborate,1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide,1-butyl-3-methylimidazolium tricyanomethane, 1-ethyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoliumtetracyanoborate, 1-ethyl-3-methylimidazoliumtris(pentafluoroethyl)trifluorophosphate, 1-methyl-3-octylimidazoliumtriflate, ethyldimethyl-(2-methoxyethyl)ammoniumtris(pentafluoroethyl)trifluorophosphate, tributylmethylammoniumdicyanamide, tricyclohexyltetradecylphosphoniumtris(pentafluoroethyl)trifluorophosphate, and1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

Embodiment 67

A method of starting up a selective hydrogenation reactor, the reactorhousing one or more catalyst beds each containing a catalyst suitablefor selectively hydrogenating acetylene in a process gas comprising atleast 10 mol. % ethylene, at least 1 ppm acetylene, and at least 5 mol.% hydrogen, the method comprising

-   -   providing each catalyst bed at no more than a first temperature,        the catalyst of the catalyst bed being in contact with a first        gas, the first gas being non-reactive in the presence of the        catalyst at the first temperature;    -   in the presence of the first gas, heating each catalyst bed to        at least a second temperature, the second temperature being at        least 20 degrees greater than the first temperature, the first        gas being non-reactive in the presence of the catalyst at the        second temperature; and then    -   changing the composition of the gas in contact with the catalyst        from the first gas to a flow of the process gas while the        catalyst bed is at least at the second temperature; and    -   allowing the process gas to flow through the catalyst bed until        a concentration of acetylene at an outlet of the reactor is less        than 1 ppm.

Embodiment 68

The method of embodiment 67, wherein the concentration of acetylene atan outlet of the reactor is less than 1 ppm within six hours (e.g.,within four hours or even within two hours) of process gas beingintroduced to the one or more catalyst beds.

Embodiment 69

The method of embodiment 67 or embodiment 68, wherein the catalyst ofeach catalyst bed has not been contacted in the reactor with carbonmonoxide in an amount in excess of 100 ppm, and wherein the methodincludes refraining from adding carbon monoxide to the process gas.

Embodiment 70

A method of starting up a selective hydrogenation reactor, the reactorhousing one or more catalyst beds each containing a catalyst suitablefor selectively hydrogenating acetylene in a process gas comprising atleast 10 mol. % ethylene, at least 1 ppm acetylene, and at least 5 mol.% hydrogen, the method comprising

-   -   providing each catalyst bed at no more than a first temperature,        the catalyst of the catalyst bed being in contact with the        process gas;    -   in the presence of the process gas, heating each catalyst bed to        at least a second temperature, the second temperature being at        least 20 degrees greater than the first temperature, the heating        of each catalyst bed being performed at a rate in the range of        at least 3° C./hour; and    -   allowing the process gas to flow through the catalyst bed until        a concentration of acetylene at an outlet of the reactor is less        than 1 ppm.

Embodiment 71

The method of embodiment 70, wherein the rate is in the range of 3-20°C./hour, e.g., 3-15° C./hour or 3-12° C./hour.

Embodiment 72

The method of embodiment 70, wherein the rate is in the range of 6-20°C./hour, e.g., 6-15° C./hour or 6-12° C./hour.

Embodiment 73

The method of embodiment 70, wherein the rate is in the range of 9-20°C./hour, e.g., 9-15° C./hour.

Embodiment 74

A method of starting up a selective hydrogenation reactor, the reactorhousing one or more catalyst beds each containing a catalyst suitablefor selectively hydrogenating acetylene in a process gas comprising atleast 10 mol. % ethylene, at least 1 ppm acetylene, and at least 5 mol.% hydrogen, the method comprising;

-   -   providing the reactor with each catalyst bed having its catalyst        in contact with a first gas, the first gas being non-reactive in        the presence of the catalyst at the first temperature, wherein        the catalyst has not been contacted in the reactor with a carbon        monoxide-containing gas having a carbon monoxide concentration        in excess of 2000 ppm; and    -   introducing a flow of the process gas to the one or more        catalyst beds, and refraining from adding carbon monoxide to the        process gas.

Embodiment 75

The method of embodiment 74, further comprising raising the catalyst bedtemperature of each catalyst bed from no more than a first temperatureto at least a second temperature.

Embodiment 76

The method of embodiment 75, wherein the catalyst bed temperature(s) areraised before the process gas is introduced.

Embodiment 77

The method of claim 75, wherein the catalyst bed temperature(s) areraised after the process gas is introduced.

Embodiment 78

The method of claim 75, wherein the process gas is introduced while thecatalyst bed temperature(s) are raised.

Embodiment 79

The method of any of embodiments 75-78, further comprising, afterraising the temperature to at least the second temperature, flowingprocess gas through the one or more catalyst beds until a reactoreffluent has less than 1 ppm (e.g., less than 0.5 ppm) acetylene.

Embodiment 80

The method according to any of embodiments 67-79, wherein the firsttemperature is no more than 50° C., e.g., in the range of 31-50° C. or35-50° C., or 40-50° C., or 45-50° C.

Embodiment 81

The method according to any of embodiments 67-79, wherein the firsttemperature is no more than 45° C., e.g., in the range of 31-45° C. or35-45° C., or 40-45° C.

Embodiment 82

The method according to any of embodiments 67-79, wherein the firsttemperature is no more than 40° C., e.g., in the range of 31-40° C. or35-40° C.

Embodiment 83

The method according to any of embodiments 67-79, wherein the firsttemperature is no more than 30° C., or no more than 25° C.

Embodiment 84

A method of starting up a selective hydrogenation reactor, the reactorhousing one or more catalyst beds each containing a catalyst suitablefor selectively hydrogenating acetylene in a process gas comprising atleast 10 mol. % ethylene, at least 1 ppm acetylene, and at least 5 mol.% hydrogen, the method comprising

-   -   drying the one or more catalyst beds at a temperature of at        least 50° C.; then cooling each dried catalyst bed to a first        temperature in the range of 31-50° C., and contacting the        catalyst of each catalyst with the process gas at the first        temperature; then    -   in the presence of the process gas, heating each catalyst bed to        at least a second temperature, the second temperature being at        least 20 degrees greater than the first temperature; and    -   allowing the process gas to flow through the catalyst bed until        a concentration of acetylene at an outlet of the reactor is less        than 1 ppm.

Embodiment 85

A method according to embodiment 84, wherein the first temperature iswithin the range of 35° C. to 50° C., e.g., 40° C. to 50° C., or 45° C.to 50° C.

Embodiment 86

A method according to embodiment 84, wherein the first temperature iswithin the range of 31° C. to 45° C., e.g., 35° C. to 45° C., or 40° C.to 45° C.

Embodiment 87

A method according to embodiment 84, wherein the first temperature iswithin the range of 31° C. to 40° C., e.g., 35° C. to 40° C.

Embodiment 88

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 40° C. to 140° C.

Embodiment 89

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 40° C. to 100° C.

Embodiment 90

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 40° C. to 90° C.

Embodiment 91

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 50° C. to 90° C.

Embodiment 92

A method according to any of embodiments v, wherein the secondtemperature is within the range of 50° C. to 100° C.

Embodiment 93

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 20° C. to 130° C., e.g., in the rangeof 20° C. to 120° C., or 20° C. to 110° C., or 20° C. to 100° C., or 20°C. to 90° C.

Embodiment 94

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 40° C. to 140° C., e.g., 40° C. to130° C., or 40° C. to 120° C., or 40° C. to 110° C.

Embodiment 95

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 50° C. to 140° C., e.g., 50° C. to130° C., or 50° C. to 120° C., or 50° C. to 110° C.

Embodiment 96

A method according to any of embodiments 67-87, wherein the secondtemperature is within the range of 60° C. to 140° C., e.g., 60° C. to130° C., or 60° C. to 120° C., or 60° C. to 110° C., or 60° C. to 100°C., or 60° C. to 90° C.

Embodiment 97

A method according to any of embodiments 67-96, wherein the secondtemperature is at least 30° C. greater (e.g., at least 40° C. greater)than the first temperature.

Embodiment 98

A method according to any of embodiments 67-96, wherein the secondtemperature is at least 50° C. greater (e.g., at least 60° C. greater)than the first temperature.

Embodiment 99

The method according to any of embodiments 67-98, wherein thetemperature of each catalyst bed is raised from no more than the firsttemperature to at least the second temperature over a time period of nomore than 10 hours, e.g., no more than six hours.

Embodiment 100

A method according to any of embodiments 67-69, 74-83 and 88-99, whereinthe first gas includes no more than 1 ppm acetylene (e.g., no more than0.5 ppm).

Embodiment 101

A method according to any of embodiments 67-100, wherein the process gasincludes at least 10 ppm CO.

Embodiment 102

A method according to any of embodiments 67-100, wherein the process gasis otherwise as described with respect to one or more of embodiments1-66.

Embodiment 103

A method according to any of embodiments 67-69, 74-83 and 88-102,wherein each catalyst bed is changed from contacting the first gas tocontacting the process gas over a time period of no more than 10 hours,e.g., no more than six hours, e.g., in the range of 2-10 hours, 4-10hours, or 3-6 hours.

Embodiment 104

The method according to any of embodiments 67-104, wherein the catalystis as described in one or more of embodiments 1-66 Embodiment 105. Amethod according to any of embodiments 1-104, further comprising, beforeintroducing the process gas to the bed or contacting the catalystcomposition with the process gas, reducing the catalyst (e.g., with aflow of a hydrogen-containing gas).

Embodiment 106

A hydrogenation catalyst composition comprising:

-   -   a porous support, present in the composition in an amount within        the range of 90 wt. % to 99.9 wt. %;    -   palladium, present in the composition in an amount within the        range of 0.02 wt. % to 0.5 wt. % (e.g., within the range of 0.03        wt. % to 0.4 wt. %, or 0.04 wt. % to 0.3 wt. %), calculated on        an elemental mass basis; and    -   one or more ionic liquids, present in the composition in a        combined amount up to 10 wt. %.

Embodiment 107

The catalyst composition of embodiment 106, wherein palladium is presentin the composition in an amount within the range of 0.02 wt. % to 0.5wt. %, for example, 0.02 wt. % to 0.4 wt. %, or 0.02 wt. % to 0.3 wt. %,or 0.02 wt. % to 0.2 wt. %, or 0.02 wt. % to 0.15 wt. %.

Embodiment 108

The catalyst composition of embodiment 106, wherein palladium is presentin the composition in an amount within the range of 0.04 wt. % to 0.5wt. %, for example, 0.04 wt. % to 0.4 wt. %, or 0.04 wt. % to 0.3 wt. %,or 0.04 wt. % to 0.2 wt. %, or 0.04 wt. % to 0.15 wt. %.

Embodiment 109

The catalyst composition of embodiment 106, wherein palladium is presentin the composition in an amount within the range of 0.05 wt. % to 0.5wt. %, for example, 0.05 wt. % to 0.4 wt. %, or 0.05 wt. % to 0.3 wt. %,or 0.05 wt. % to 0.2 wt. %, or 0.05 wt. % to 0.15 wt. %.

Embodiment 110

The catalyst composition of embodiment 106, wherein palladium is presentin the composition in an amount within the range of 0.06 wt. % to 0.5wt. %, for example, 0.06 wt. % to 0.4 wt, or 0.06 wt. % to 0.3 wt, or0.06 wt. % to 0.2 wt. %, or 0.06 wt. % to 0.15 wt. %.

Embodiment 111

The catalyst composition of embodiment 106, wherein palladium is presentin the composition in an amount within the range of 0.08 wt. % to 0.5wt. %, for example, 0.08 wt. % to 0.4 wt. %, or 0.08 wt. % to 0.3 wt. %,or 0.07 wt. % to 0.2 wt. %, or 0.07 wt. % to 0.15 wt. %.

Embodiment 112

A hydrogenation catalyst composition comprising:

-   -   a porous support, present in the composition in an amount within        the range of 90 wt. % to 99.9 wt. %, having a BET surface area        of no more than 10 m²/g and a pore volume of at least 0.1 mL/g;    -   palladium, present in the composition in an amount within the        range of at least 0.02 wt. %, calculated on an elemental mass        basis; and    -   one or more ionic liquids, present in the composition in a        combined amount up to 10 wt. %.

Embodiment 113

The hydrogenation catalyst of embodiment 112, comprising palladium in anamount of at least 0.03 wt. %, or at least 0.04 wt. %, or at least 0.05wt. %, or at least 0.06 wt. %, or at least 0.07 wt. %, or at least 0.08wt. %, or at least 0.09 wt. %, or at least 0.1 wt. %, or at least 0.11wt. %, or at least 0.12 wt. %, or at least 0.13 wt. %, or at least 0.14wt. %, or at least 0.15 wt. %.

Embodiment 114

The hydrogenation catalyst of embodiment 112, comprising palladium in anamount of no more than 0.5 wt. % (e.g., no more than 0.4 wt. %, or nomore than 0.3 wt. %, or no more than 0.2 wt. %).

Embodiment 115

The hydrogenation catalyst of embodiment 112, comprising palladium in anamount within the range of 0.02 wt. % to 0.5 wt. %, or 0.02 wt. % to0.45 wt. %, or 0.03 wt. % to 0.4 wt. %, or 0.03 wt. % to 0.35 wt. %, or0.04 wt. % to 0.3 wt. %, or 0.04 wt. % to 0.25 wt. %.

Embodiment 116

The catalyst composition of any of embodiments 106-115, furthercomprising at least one promoter (e.g., silver, gold, zinc, tin, lead,gallium, cadmium, copper, bismuth, sodium, cesium, or potassium),present in the composition in an amount within the range of 0.05 wt. %to 0.25 wt. %, e.g., 0.08 wt. % to 0.25 wt. %, or 0.1 wt. % to 0.25 wt.%, calculated on an elemental mass basis.

Embodiment 117

The hydrogenation catalyst of any of embodiments 106-116, wherein theporous support has a BET surface area within the range of 2 m²/g to 10m²/g.

Embodiment 118

The hydrogenation catalyst of any of embodiments 106-116, the poroussupport has a BET surface area within the range of 2 m²/g to 9 m²/g, or2 m²/g to 8 m²/g, or 2 m²/g to 7 m²/g, or 2 m²/g to 6 m²/g, or 2 m²/g to5 m²/g, or 3 m²/g to 10 m²/g, or 4 m²/g to 10 m²/g, or 5 m²/g to 10m²/g, or 6 m²/g to 10 m²/g, or 2 m²/g to 6 m²/g, or 3 m²/g to 7 m²/g, or4 m²/g to 8 m²/g, or 5 m²/g to 9 m²/g.

Embodiment 119

The hydrogenation catalyst of any of embodiments 106-118, wherein theporous support has a pore volume within the range of 0.10 mL/g to 1.0mL/g.

Embodiment 120

The hydrogenation catalyst of any of 106-118, wherein the porous supporthas a pore volume within the range of 0.10 mL/g to 0.80 mL/g, or 0.20mL/g to 0.80 mL/g, or 0.30 mL/g to 0.80 mL/g, or 0.20 mL/g to 0.70 mL/g,or 0.30 mL/g to 0.70 mL/g.

Embodiment 121

A hydrogenation catalyst composition comprising:

-   -   a porous support, present in the composition in an amount within        the range of 90 wt. % to 99.9 wt. %;    -   palladium, present in the composition in an amount within the        range of at least 0.02 wt. %, calculated on an elemental mass        basis; and    -   one or more ionic liquids, present in the composition in a        combined amount up to 10 wt. %,    -   wherein the hydrogenation catalyst has a BET surface area of no        more than 10 m²/g and a pore volume of at least 0.05 mL/g.

Embodiment 122

The hydrogenation catalyst of embodiment 121, comprising palladium in anamount of at least 0.03 wt. %, or at least 0.04 wt. %, or at least 0.05wt. %, or at least 0.06 wt. %, or at least 0.07 wt. %, or at least 0.08wt. %, or at least 0.09 wt. %, or at least 0.1 wt. %, or at least 0.11wt. %, or at least 0.12 wt. %, or at least 0.13 wt. %, or at least 0.14wt. %, or at least 0.15 wt. %.

Embodiment 123

The hydrogenation catalyst of embodiment 121 or embodiment 122,comprising palladium in an amount of no more than 0.5 wt. % (e.g., nomore than 0.4 wt. %, or no more than 0.3 wt. %, or no more than 0.2 wt.%).

Embodiment 124

The hydrogenation catalyst of embodiment 121, comprising palladium in anamount within the range of 0.02 wt. % to 0.5 wt. %, or 0.02 wt. % to0.45 wt. %, or 0.03 wt. % to 0.4 wt. %, or 0.03 wt. % to 0.35 wt. %, or0.04 wt. % to 0.3 wt. %, or 0.04 wt. % to 0.25 wt. %.

Embodiment 125

The hydrogenation catalyst of any of embodiments 121-124, furthercomprising at least one promoter (e.g., silver, gold, zinc, tin, lead,gallium, cadmium, copper, bismuth, sodium, cesium, or potassium),present in the composition in an amount within the range of 0.05 wt. %to 0.25 wt. %, e.g., 0.08 wt. % to 0.25 wt. %, or 0.1 wt. % to 0.25 wt.%, calculated on an elemental mass basis.

Embodiment 126

The hydrogenation catalyst of any of embodiments 121-125, having a BETsurface area within the range of 2 m²/g to 10 m²/g.

Embodiment 127

The hydrogenation catalyst of any of embodiments 121-125, having a BETsurface area within the range of 2 m²/g to 9 m²/g, or 2 m²/g to 8 m²/g,or 2 m²/g to 7 m²/g, or 2 m²/g to 6 m²/g, or 2 m²/g to 5 m²/g, or 3 m²/gto 10 m²/g, or 4 m²/g to 10 m²/g, or 5 m²/g to 10 m²/g, or 6 m²/g to 10m²/g, or 2 m²/g to 6 m²/g, or 3 m²/g to 7 m²/g, or 4 m²/g to 8 m²/g, or5 m²/g to 9 m²/g.

Embodiment 128

The hydrogenation catalyst of any of embodiments 121-127, having a porevolume within the range of 0.05 mL/g to 1.0 mL/g.

Embodiment 129

The hydrogenation catalyst of any of embodiments 121-127, having a porevolume within the range of 0.05 mL/g to 0.4 mL/g.

Embodiment 130

The hydrogenation catalyst of any of embodiments 121-129, having a porevolume within the range of 0.10 mL/g to 1.0 mL/g, e.g., 0.10 mL/g to0.80 mL/g, or 0.10 to 0.60 mL/g, or 0.10 to 0.40 mL/g, or 0.10 to 0.30mL/g.

Embodiment 131

The hydrogenation catalyst of any of embodiments 121-129, having a porevolume within the range of 0.20 mL/g to 1.0 mL/g, e.g., 0.20 mL/g to0.80 mL/g, or 0.20 to 0.60 mL/g, or 0.20 to 0.40 mL/g, or 0.20 to 0.35mL/g.

Embodiment 132

The hydrogenation catalyst of any of embodiments 121-129, having a porevolume within the range of 0.40 mL/g to 1.0 mL/g, e.g., 0.40 mL/g to0.80 mL/g, or 0.40 to 0.60 mL/g.

Embodiment 133

They hydrogenation catalyst of any of embodiments 121-132, wherein thedifference between the pore volume of the support and the pore volume ofthe catalyst (i.e., including the palladium, any promoters and the ionicliquid) is in the range of 10-90% of the pore volume of the support.

Embodiment 134

They hydrogenation catalyst of any of embodiments 121-132, wherein thedifference between the pore volume of the support and the pore volume ofthe catalyst (i.e., including the palladium, any promoters and the ionicliquid) is in the range of 10-80% of the pore volume of the support,e.g., 20-80%, or 30-80%, or 40-80% of the pore volume of the support.

Embodiment 135

They hydrogenation catalyst of any of embodiments 121-132, wherein thedifference between the pore volume of the support and the pore volume ofthe catalyst (i.e., including the palladium, any promoters and the ionicliquid) is in the range of 10-70% of the pore volume of the support,e.g., 20-70%, or 30-70%, or 40-70%; or in the range of 10-60% of thepore volume of the support, e.g., 20-60%, or 30-60%, or 40-60%.

Embodiment 136

The hydrogenation catalyst of any of claims 106-135, wherein the ionicliquid is present in an amount in the range of 0.1 wt. % to 10 wt. %,e.g., 0.1 wt. % to 8 wt. %, or 0.1 wt. % to 6 wt. %, or 0.1 wt. % to 4wt. %, or 0.1 wt. % to 3 wt. %, or 0.1 wt. % to 2 wt. %, or 0.1 wt. % to1 wt. %.

Embodiment 137

The hydrogenation catalyst of any of embodiments 106-135, wherein theionic liquid is present in an amount in the range of 0.2 to 3 wt. %.

Embodiment 138

The hydrogenation catalyst of any of embodiments 106-135, wherein theionic liquid is present in an amount in the range of 0.5 to 4 wt. %.

Embodiment 139

The hydrogenation catalyst of any of embodiments 106-138, having silveras a promoter.

Embodiment 140

The hydrogenation catalyst of any of embodiments 106-139, wherein theporous support is a porous alumina support, e.g., a porous alpha aluminasupport.

Embodiment 141

The hydrogenation catalyst of any of embodiments 106-140, wherein theshell thickness of the ionic liquid at an outer surface of the catalystis in the range of 10 to 2000 μm, e.g., 100 to 1000 μm, or 100 to 800μm.

Embodiment 142

The hydrogenation catalyst of any of embodiments 106-138, wherein the atleast one ionic liquid is selected from 1-butyl-3-methylimidazoliumtriflate, 1-ethyl-3-methylpyridinium ethylsulfate,1-butyl-1-methylpyrrolidinium triflate, 1-butyl-2,3-dimethylimidazoliumtriflate, 1-butyl-3-methylimidazolium tricyanomethane,1-butyl-3-methylimidazolium methylsulfate, 1-butyl-3-methylimidazoliumoctylsulfate, 1-butyl-3-methylimidazolium tetrafluoroborate,1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazoliummethylphosphonate, 1-ethyl-3-methylimidazolium triflate,1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide,1-butyl-1-methylpyrrolidinium tetracyanoborate,1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide,1-butyl-3-methylimidazolium tricyanomethane, 1-ethyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoliumtetracyanoborate, 1-ethyl-3-methylimidazoliumtris(pentafluoroethyl)trifluorophosphate, 1-methyl-3-octylimidazoliumtriflate, ethyldimethyl-(2-methoxyethyl)ammoniumtris(pentafluoroethyl)trifluorophosphate, tributylmethylammoniumdicyanamide, tricyclohexyltetradecylphosphoniumtris(pentafluoroethyl)trifluorophosphate, and1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

Embodiment 143

Any of the processes of embodiments 1-59 and 67-105, using the catalystas described in any of embodiments 106-142.

What is claimed is:
 1. A method for selectively hydrogenating acetylene,the method comprising contacting a catalyst composition with a processgas comprising ethylene, present in the process gas in an amount of atleast 10 mol. %; acetylene, present in the process gas in an amount ofat least about 1 ppm, calculated on a molar basis; hydrogen, present inthe process gas in amount of at least 5 mol. %; and 0 ppm to 120 ppmcarbon monoxide, calculated on a molar basis; wherein the catalystcomposition comprises a porous support, present in the catalystcomposition in an amount within a range of 90 wt. % to 99.9 wt. %;palladium, present in the catalyst composition in an amount within arange of at least 0.02 wt. %, calculated on an elemental mass basis; andone or more ionic liquids, present in the catalyst composition in acombined amount in a range of 0.1 wt. % to 10 wt. %; wherein the processgas is contacted with the catalyst composition at a gas hourly spacevelocity (GHSV) based on a total catalyst volume in one bed or multiplebeds in a range of 7,500 h⁻¹ to 30,000 h⁻¹; and wherein at least 90% ofthe acetylene present in the process gas is hydrogenated, and no morethan 1 mol. % of the total of acetylene and ethylene present in theprocess gas is converted to ethane.
 2. A method according to claim 1,wherein the gas hourly space velocity is in a range of 10,000 h⁻¹ to30,000 h⁻¹.
 3. A method according to claim 1, wherein the contacting isconducted at a temperature within a range of 20° C. to 140° C.
 4. Amethod according to claim 1, wherein the contacting is conducted at atemperature within a range of 40° C. to 100° C.
 5. A method according toclaim 1, wherein carbon monoxide is present in the process gas in anamount in a range of 0 ppm to 90 ppm, calculated on a molar basis.
 6. Amethod according to claim 1, wherein at least 95% of the acetylenepresent in the process gas is hydrogenated.
 7. A method according toclaim 1, wherein an amount of ethane in the product of the selectivehydrogenation is no more than 0.5 mol. % greater than the amount ofethane in the process gas.
 8. A method according to claim 1, whereinethylene is present in the process gas in an amount of at least 20 mol.%.
 9. A method according to claim 1, wherein acetylene is present in theprocess gas in an amount of at least 500 ppm, calculated on a molarbasis.
 10. A method according to claim 1, wherein hydrogen is present inthe process gas in an amount in a range of 5 mol. % to 35 mol. %. 11.The method according to claim 1, wherein the process gas contains nomore than 5 mol. % of carbon-containing components other than C₁components, C₂ components and C₃ components.
 12. A method according toclaim 1, wherein the catalyst composition comprises a porous supportselected from alumina, silica, titania, and mixtures thereof, present inthe catalyst composition in an amount within a range of 90 wt. % to 99.9wt. %.
 13. A method according to claim 1, wherein the catalystcomposition comprises palladium in an amount of at least 0.05 wt. %. 14.A method according to claim 1, wherein the catalyst compositioncomprises the at least one ionic liquid in a total amount in a range of0.1 wt. % to 2 wt. %.
 15. A method according to claim 1, wherein the atleast one ionic liquid is selected from 1-butyl-3-methylimidazoliumtriflate, 1-ethyl-3-methylpyridinium ethylsulfate,1-butyl-1-methylpyrrolidinium triflate, 1-butyl-2,3-dimethylimidazoliumtriflate, 1-butyl-3-methylimidazolium tricyanomethane,1-butyl-3-methylimidazolium methylsulfate, 1-butyl-3-methylimidazoliumoctylsulfate, 1-butyl-3-methylimidazolium tetrafluoroborate,1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazoliummethylphosphonate, 1-ethyl-3-methylimidazolium triflate,1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide,1-butyl-1-methylpyrrolidinium tetracyanoborate,1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide,1-butyl-3-methylimidazolium tricyanomethane, 1-ethyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoliumtetracyanoborate, 1-ethyl-3-methylimidazoliumtris(pentafluoroethyl)trifluorophosphate, 1-methyl-3-octylimidazoliumtriflate, ethyldimethyl-(2-methoxyethyl)ammoniumtris(pentafluoroethyl)trifluorophosphate, tributylmethylammoniumdicyanamide, tricyclohexyltetradecylphosphoniumtris(pentafluoroethyl)trifluorophosphate, and1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.
 16. Themethod according to claim 1, wherein the catalyst composition comprises:a porous support, present in the catalyst composition in an amountwithin a range of 90 wt. % to 99.9 wt. %; palladium, present in thecatalyst composition in an amount within a range of 0.02 wt. % to 0.5wt. %, calculated on an elemental mass basis; and one or more ionicliquids, present in the catalyst composition in a combined amount in arange of 0.1 wt. % to 2 wt. %.
 17. The method according to claim 1,wherein the catalyst composition has a BET surface area of no more than10 m²/g and a pore volume of at least 0.05 mL/g.
 18. A method accordingto claim 1, wherein carbon monoxide is present in the process gas in anamount in a range of 50 to 100 ppm, calculated on a molar basis.
 19. Amethod according to claim 1, wherein carbon monoxide is present in theprocess gas in an amount in a range of 25 wt. % to 80 ppm, calculated ona molar basis.
 20. A method according to claim 1, wherein carbonmonoxide is present in the process gas in an amount in a range of 25-90ppm, calculated on a molar basis.
 21. A method according to claim 1,wherein the contacting is conducted at a temperature within a range of20° C. to 140° C.; carbon monoxide is present in the process gas in anamount of 25-90 ppm, calculated on a molar basis; at least 95% of theacetylene present in the process gas is hydrogenated; an amount ofethane in the product of the selective hydrogenation is no more than 0.5mol. % greater than the amount of ethane in the process gas; ethylene ispresent in the process gas in an amount of at least 20 mol. %; acetyleneis present in the process gas in an amount of at least 500 ppm,calculated on a molar basis; hydrogen is present in the process gas inan amount in a range of 5 mol. % to 35 mol. %; the process gas containsno more than 5 mol. % of carbon-containing components other than C₁components, C₂ components and C₃ components; the catalyst compositioncomprises a porous support selected from alumina, silica, titania, andmixtures thereof, present in the catalyst composition in an amountwithin a range of 90 wt. % to 99.9 wt. %, palladium in an amount of atleast 0.05 wt. %, the at least one ionic liquid in a total amount in arange of 0.1 wt. % to 2 wt. %.
 22. The method according to claim 1,wherein the method for selectively hydrogenating acetylene is configuredas a front-end hydrogenation.